Multi-component stent-graft system for implantation in a blood vessel with multiple branches

ABSTRACT

A multi-component stent-graft system (10) comprises first, second, and third generally tubular stent-grafts (20, 22, 24), which are configured to assume radially-expanded states. The first stent-graft (20) is shaped so as to define a first lateral opening (34) when in its radially-expanded state. The second stent-graft (22) is shaped so as to define a second lateral opening (44) when in its radially-expanded state. The first and second stent-grafts (20, 22) are configured such that the second stent-graft (22) forms a blood-impervious seal with the first stent-graft (20) around the first lateral opening (34) when the second stent-graft (22) is disposed therethrough, and the first and the second stent-grafts (20, 22) are in their radially-expanded states. The second and the third stent-grafts (22, 24) are configured such that the third stent-graft (24) forms a blood-impervious seal with the second stent-graft (22) around the second lateral opening (44) when the third stent-graft (24) is disposed therethrough, and the second and third stent-grafts (22, 24) are in their radially-expanded states. Other embodiments are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application claims priority from U.S. ProvisionalApplication 61/264,861, filed Nov. 30, 2009, entitled, “A multicomponent stent graft system for implantation into a vessel withmultiple adjacent branches and methods for using same,” which isincorporated herein by reference.

FIELD OF THE APPLICATION

This present application relates generally to prostheses and surgicalmethods, and specifically to tubular prostheses, including endovasculargrafts and stent-grafts, and surgical techniques for using theprostheses to maintain patency of body passages such as blood vessels,and treating aneurysms.

BACKGROUND OF THE APPLICATION

Endovascular prostheses are sometimes used to treat aortic aneurysms.Such treatment includes implanting a stent or stent-graft within thediseased vessel to bypass the anomaly. An aneurysm is a sac formed bythe dilation of the wall of the artery. Aneurysms may be congenital, butare usually caused by disease or, occasionally, by trauma. Aorticaneurysms which commonly form between the renal arteries and the iliacarteries are referred to as abdominal aortic aneurysms (“AAAs”). Otheraneurysms occur in the aorta, such as thoracic aortic aneurysms (“TAAs”)and aortic uni-iliac (“AUI”) aneurysms.

PCT Publication WO 2008/107885 to Shalev et al., and US PatentApplication Publication 2010/0063575 to Shalev et al. in the US nationalstage thereof, which are incorporated herein by reference, describe amultiple-component expandable endoluminal system for treating a lesionat a bifurcation, including a self expandable tubular root member havinga side-looking engagement aperture, and a self expandable tubular trunkmember comprising a substantially blood impervious polymeric linersecured therealong. Both have a radially-compressed state adapted forpercutaneous intraluminal delivery and a radially-expanded state adaptedfor endoluminal support.

US Patent Application Publication 2009/0254170 to Hartley et al.describes a deployment system for introducing stent grafts which have aside arm or into which a side arm can be deployed. For instance thestent graft can be deployed into the thoracic arch of a patient. Thedeployment system includes an introducer, an auxiliary catheter disposedwithin the introducer and an auxiliary guide wire disposed within theauxiliary catheter. The auxiliary guide wire extends to adjacent theproximal end of the introducer an can be extended from the proximal endof the introducer so that it can be snared from a side branch artery toassist with deployment of a side arm of the stent graft into the sideartery or for the deployment of a side arm stent graft into the stentgraft.

The following references may be of interest:

U.S. Pat. No. 4,938,740 to Melbin

U.S. Pat. No. 5,824,040 to Cox et al.

U.S. Pat. No. 7,044,962 to Elliott

US Patent Application Publication 2004/0106978 to Greenberg et al.

US Patent Application Publication 2006/0229709 to Morris et al.

US Patent Application Publication 2006/0241740 to Vardi et al.

US Patent Application Publication 2007/0233229 to Berra et al.

US Patent Application Publication 2008/0109066 to Quinn

US Patent Application Publication 2008/0114445 to Melsheimer et al.

US Patent Application Publication 2010/0161026 to Brocker et al.

PCT Publication WO 2004/017868 to Hartley

PCT Publication WO 2006/007389 to Greenberg et al.

PCT Publication WO 2007/084547 to Godlewski et al.

PCT Publication WO 2008/042266 to Yi Tseng et al.

PCT Publication WO 2008/047092 to Goddard et al.

PCT Publication WO 2008/140796 to Hartley et al.

PCT Publication WO 2010/024869 to Hartley et al.

PCT Publication WO 2010/024879 to Hartley et al.

PCT Publication WO 2010/062355 to Kolbel et al.

European Publication EP 1 177 780 A2 to Barone

European Publication EP 1 325 716 A1 to Depalma et al.

Canadian Publication CA 2 497 704 to Nelson

SUMMARY OF APPLICATIONS

Some applications of the present invention provide a multi-componentstent-graft system for treating a thoracic aortic aneurysm, such as ofthe aortic arch. The system is configured to be deployed in the thoracicaorta and in one or more of the branches of the aortic arch (thebrachiocephalic artery, the left common carotid artery, and/or the leftsubclavian artery). The multi-component stent-graft comprises first andsecond stent-grafts, and optionally a third stent-graft and/or a fourthstent-graft. Typically, the first stent-graft is shaped so as to defineat least one first lateral opening. The second stent-graft is typicallyconfigured to be disposed through the first lateral opening, such thatthe second stent-graft forms a blood-impervious seal with the firststent-graft around the first lateral opening.

The multi-component stent-graft system is configured to be deployed in astraightforward procedure that readily accommodates ordinary anatomicalvariances among different patients. For example, the locations of thebifurcations of the three branches of the aortic arch vary amongpatients. The stent-grafts of the system are assembled in situ toaccommodate the dimensions of the particular patient's anatomy,generally without requiring prior customization of the stent-grafts orin situ modifications to the stent-grafts, which might be expensiveand/or complex.

Typically, upon deployment, the multi-component stent-graft systemdefines a blood-flow path from the ascending aorta, over the aorticarch, and to the descending aorta. The stent-graft system additionallyprovides blood-flow paths to the three branches of the aortic arch.

For some applications, the first stent-graft is configured to bepositioned such that a proximal portion thereof, including a proximalend thereof, is positioned in the upper part of the descending aorta,and a distal portion thereof, including a distal end thereof, ispositioned in one of the branches of the aortic arch. When thuspositioned, the first lateral opening is disposed in the aortic archfacing upstream, generally toward the ascending aorta.

For some applications, the distal portion of the first stent-graft ispositioned in the left subclavian artery. The second stent-graft isadvanced up the descending aorta, through the proximal portion of thefirst-stent-graft, out of the first lateral opening, and into a secondone of the branches of the aortic arch, such as the left common carotidartery. A proximal portion of the second stent-graft, including aproximal end thereof, is positioned within the first stent-graft in theupper part of the descending aorta, and a distal portion of the secondstent-graft, including a distal end thereof, is positioned in the leftcommon carotid artery. It is noted that this technique for positioningthe second stent-graft readily accommodates the particular anatomicallocation of the second branch of the aortic arch (including with respectto the first branch), without requiring either the first or the secondstent-graft to be customized (in shape or size) for the particularpatient.

For some applications in which the third stent-graft is provided, thesecond stent-graft is shaped so as to define a second lateral opening,which faces upstream, generally toward the ascending aorta, uponplacement of the second stent-graft as described above. The thirdstent-graft is advanced up the descending aorta and into a third one ofthe branches of the aortic arch, such as the brachiocephalic artery. Aproximal portion of the third stent-graft is positioned within thesecond stent-graft in the aortic arch, and a distal portion of the thirdstent-graft, including a distal end thereof, is positioned in thebrachiocephalic artery. It is noted that this technique for positioningthe third stent-graft readily accommodates the particular anatomicallocation of the third branch of the aortic arch (including with respectto the first and second branches), without requiring either the first,second, or third stent-graft to be customized (in shape or size) for theparticular patient.

For some applications in which the fourth stent-graft is provided, thethird stent-graft is shaped so as to define a third lateral opening,which faces upstream, generally toward the ascending aorta, uponplacement of the third stent-graft as described above. The fourthstent-graft is advanced up the descending aorta and into the aortic archand/or the upper part of the ascending aorta. A proximal portion of thefourth stent-graft is positioned within the third stent-graft in theaortic arch, and a distal portion of the fourth stent-graft, including adistal end thereof, is positioned in the aortic arch and/or the upperpart of the ascending aorta.

For other applications, the first stent-graft is shaped so as to defineproximal and distal superior first lateral openings, and a distalinferior first lateral opening. A proximal portion of the firststent-graft, including a proximal end thereof, is positioned in theupper part of the descending aorta; a middle portion of the firststent-graft is positioned in the aortic arch; and a distal portion ofthe first stent-graft, including a distal end thereof, is positioned inthe brachiocephalic artery. The proximal superior first lateral openingfaces toward and is aligned with the left subclavian artery, and thedistal superior first lateral opening faces toward and is aligned withthe left common carotid artery. The distal inferior first lateralopening is disposed within the aortic arch facing upstream, generallytoward the ascending aorta. It is noted that the distance between thebifurcations of the left common carotid artery and the left subclavianartery does not generally vary substantially among patients, so thegenerally fixed relative locations of the proximal and distal superiorfirst lateral openings does not generally present difficulties duringthe procedure, particularly if some space is provided between thesuperior openings and the bifurcations to allow manipulation of thirdand fourth stent-grafts, described below. The two openings are readilyaligned with the two branches during positioning of the firststent-graft, such that placement of the distal end of the firststent-graft in the brachiocephalic artery naturally accommodates thelocation of the bifurcation of the brachiocephalic artery with respectto the locations of the bifurcations of the left common carotid arteryand the left subclavian artery.

The second stent-graft is advanced up the descending aorta, through aproximal portion of the first-stent-graft, out of the distal inferiorfirst lateral opening, and into the aortic arch and/or the upper part ofthe ascending aorta. A proximal portion of the second stent-graft,including a proximal end thereof, is positioned within the firststent-graft in the aortic arch, and a distal portion of the secondstent-graft, including a distal end thereof, is positioned in the aorticarch and/or the upper part of the ascending aorta.

The third and fourth stent-grafts are separately advanced up thedescending aorta (in a single delivery tool, or two separate deliverytools) and through a proximal portion of the first stent-graft. One ofthese stent-grafts is advanced out of the proximal superior firstlateral opening into the left subclavian artery, and the other isadvanced out of the distal superior first lateral opening into the leftcommon carotid artery. Proximal portions of the third and fourthstent-grafts, including proximal ends thereof, are positioned within thefirst stent-graft in the aortic arch, and distal portions of the thirdand fourth stent-grafts, including distal ends thereof, are positionedin the left subclavian artery and the left common carotid artery,respectively.

For still other applications, the first stent-graft is shaped so as todefine a superior first lateral opening and an inferior first lateralopening. A proximal portion of the first stent-graft, including aproximal end thereof, is positioned in the upper part of the descendingaorta; a middle portion of the first stent-graft is positioned in theaortic arch; and a distal portion of the first stent-graft, including adistal end thereof, is positioned in the left common carotid artery. Thesuperior first lateral opening faces toward and is aligned with the leftsubclavian artery, and the inferior first lateral opening is disposedwithin the aortic arch facing upstream, generally toward the ascendingaorta. It is noted that this technique for positioning the firststent-graft readily accommodates the particular anatomical location ofthe left common carotid artery.

The second stent-graft is advanced up the descending aorta, through aproximal portion of the first-stent-graft, out of the superior firstlateral opening, and into the left subclavian artery. A proximal portionof the second stent-graft, including a proximal end thereof, ispositioned within the first stent-graft in the aortic arch, and a distalportion of the second stent-graft, including a distal end thereof, ispositioned in the left subclavian artery. It is noted that thistechnique for positioning the second stent-graft readily accommodatesthe particular anatomical location of the left common carotid artery.

The third stent-graft is advanced down the right subclavian artery andthe brachiocephalic artery into the upper part of the ascending aorta. Aproximal portion of the third stent-graft, including a proximal endthereof, is positioned within the brachiocephalic artery, and a distalportion of the third stent-graft, including a distal end thereof, ispositioned in the aortic arch and/or the upper part of the ascendingaorta. A third lateral opening defined by the third stent-graft isdisposed within the aortic arch facing downstream, generally toward thedescending aorta, such that the third lateral opening faces and isaligned with the inferior first lateral opening of the firststent-graft. It is noted that this technique for positioning the thirdstent-graft readily accommodates the particular anatomical location ofthe brachiocephalic artery with respect to the left subclavian arteryand the left common carotid artery.

The fourth stent-graft is advanced up the descending aorta, through aproximal portion of the first stent-graft, and out of the inferior firstlateral opening. A distal portion of the fourth stent-graft, including adistal end thereof, is positioned within the first stent-graft; aproximal portion of the fourth stent-graft, including a proximal endthereof, is positioned within third stent-graft 24; and a middle portionof fourth stent-graft 26 is positioned in the aortic arch.

Although the multi-component stent-graft system is generally describedherein as being applicable for placement in the area of the thoracicaorta, for some applications the stent-graft system is instead placed inanother area of a main body lumen and one or more branching body lumens,such as a main blood vessel and one or more branching blood vessels. Forsome applications, a method for deploying the stent-graft systemcomprises transvascularly introducing and positioning a firststent-graft such that a proximal portion of the first stent-graft,including a proximal end of the first-stent-graft, is in a proximalportion of a main blood vessel, a distal portion of the firststent-graft, including a distal end of the first stent-graft, is in abranching blood vessel that branches from the main blood vessel, and afirst lateral opening defined by the first stent-graft is disposedwithin the main blood vessel facing toward a distal portion of the mainblood vessel; and transvascularly introducing and passing a secondstent-graft through the proximal portion of the first stent-graft suchthat the second stent-graft is disposed through the first lateralopening and is disposed partially in the distal portion of the mainblood vessel, and forms a blood-impervious seal with the firststent-graft around the first lateral opening.

There is therefore provided, in accordance with an application of thepresent invention, apparatus including a multi-component stent-graftsystem, which includes:

a first generally tubular stent-graft, which is shaped so as to define afirst lateral opening when in a radially-expanded state;

a second generally tubular stent-graft, which is shaped so as to definea second lateral opening when in a radially-expanded state, wherein thefirst and second stent-grafts are configured such that the secondstent-graft forms a blood-impervious seal with the first stent-graftaround the first lateral opening when the second stent-graft is disposedtherethrough, and the first and the second stent-grafts are in theirradially-expanded states; and

a third generally tubular stent-graft, which is configured to assume aradially-expanded state, wherein the second and the third stent-graftsare configured such that the third stent-graft forms a blood-imperviousseal with the second stent-graft around the second lateral opening whenthe third stent-graft is disposed therethrough, and the second and thirdstent-grafts are in their radially-expanded states.

For some applications:

the first stent-graft includes a first generally tubular support elementand a first covering element attached to the first support element so asto at least partially cover the first support element, and the firstcovering element and the first support element are shaped so as totogether define the first lateral opening through the first stent-graftwhen the first stent-graft is in its radially-expanded state,

the second stent-graft includes a second generally tubular supportelement and a second covering element attached to the second supportelement so as to at least partially cover the second support element,and the second covering element and the second support element areshaped so as to together define the second lateral opening through thesecond stent-graft when the second stent-graft is in itsradially-expanded state, and the first and the second stent-grafts areconfigured such that the second covering element forms theblood-impervious seal with the first covering element around the firstlateral opening when the second stent-graft is disposed therethrough,and the first and the second stent-grafts are in their radially-expandedstates, and

the third stent-graft includes a third generally tubular support elementand a third covering element attached to the third support element so asto at least partially cover the third support element, and the secondand the third stent-grafts are configured such that the third coveringelement forms the blood-impervious seal with the second covering elementaround the second lateral opening when the third stent-graft is disposedtherethrough, and the second and third stent-grafts are in theirradially-expanded states.

For some applications, the first, the second, and the third coveringelements are not fixed to one another when the first, the second, andthe third stent-grafts are in their radially-compressed states. For someapplications, when the third stent-graft is disposed through the secondlateral opening and the second and the third stent-grafts are in theirradially-expanded states: a proximal portion of the third supportelement is disposed within the second stent-graft, and the thirdcovering element does not fully cover the proximal portion of the thirdsupport element, thereby allowing blood flow through the secondstent-graft.

For some applications, the second stent-graft is configured totransition, without inverting, from a radially-compressed state to itsradially-expanded state. For some applications, the third stent-graft isconfigured to transition, without inverting, from a radially-compressedstate to its radially-expanded state.

For some applications, the first, the second, and the third stent-graftsare not fixed to one other when in their radially-compressed states.

For some applications, the third stent-graft is adapted for transluminaldelivery in a radially-compressed state through, sequentially, (a) aportion of the first stent-graft, (b) the first lateral opening, (c) aportion of the second stent-graft, and (d) the second lateral opening,while the first and the second stent-grafts are in theirradially-expanded states.

For some applications, the third stent-graft is shaped so as to define athird lateral opening when in its radially-expanded state; thestent-graft system further includes a fourth generally tubularstent-graft, which is configured to assume a radially-expanded state;and the third and the fourth stent-grafts are configured such that thefourth stent-graft forms a blood-impervious seal with the thirdstent-graft around the third lateral opening when the fourth stent-graftis disposed therethrough, and the third and the fourth stent-grafts arein their radially-expanded states.

For some applications:

the third covering element and the third support element are shaped soas to together define the third lateral opening through the thirdstent-graft when the third stent-graft is in its radially-expandedstate,

the fourth stent-graft includes a fourth generally tubular supportelement and a fourth covering element, which is attached to the fourthsupport element so as to at least partially cover the fourth supportelement, and

the third and the fourth stent-grafts are configured such that thefourth covering element forms the blood-impervious seal with the thirdcovering element around the third lateral opening when the fourthstent-graft is disposed therethrough, and the third and the fourthstent-grafts are in their radially-expanded states.

For some applications, the fourth covering element and the fourthsupport element are not shaped so as to together define any lateralopenings through the fourth stent-graft when the fourth stent-graft isin its radially-expanded state.

For some applications, the first, the second, the third, and the fourthstent-grafts are configured for transluminal delivery for transport torespective sites within a body lumen when in radially-compressed states,and the fourth stent-graft is adapted for transluminal delivery in itsradially-compressed state through, sequentially, (a) a portion of thefirst stent-graft, (b) the first lateral opening, (c) a portion of thesecond stent-graft, (d) the second lateral opening, (e) a portion of thethird stent-graft, and (f) the third lateral opening, while the first,the second, and the third stent-grafts are in their radially-expandedstates.

For some applications, (a) a proximal portion of the first stent-graft,including a proximal end of the first-stent-graft, is configured to bepositioned in a proximal portion of a main blood vessel, (b) a distalportion of the first stent-graft, including a distal end of the firststent-graft, is configured to be positioned in a branching blood vesselthat branches from the main blood vessel, and (c) the first stent-graftis configured such that a first lateral opening defined by the firststent-graft is disposed within the main blood vessel facing toward adistal portion of the main blood vessel; and the second stent-graft isconfigured to be disposed partially in the distal portion of the mainblood vessel.

For some applications, the first stent-graft is shaped so as to defineexactly one first lateral opening when the first stent-graft is in itsradially-expanded state.

There is further provided, in accordance with an application of thepresent invention, apparatus including a multi-component stent-graftsystem, which includes:

a first generally tubular stent-graft, which, when unconstrained in aradially-expanded state: (a) defines a first lateral opening, and (b)has a first perimeter of a first end thereof that equals at least 200%of a second perimeter of a second end thereof; and

a second generally tubular stent-graft, which is configured to assume aradially-expanded state, wherein the first and the second stent-graftsare configured such that the second stent-graft forms a blood-imperviousseal with the first stent-graft around the first lateral opening whenthe second stent-graft is disposed therethrough, and the first andsecond stent-grafts are in their radially-expanded states.

For some applications:

the first stent-graft includes a first generally tubular support elementand a first covering element attached to the first support element so asto at least partially cover the first support element, and the firstcovering element and the first support element are shaped so as totogether define the first lateral opening through the first stent-graftwhen the first stent-graft is in its radially-expanded state, and

the second stent-graft includes a second generally tubular supportelement and a second covering element attached to the second supportelement so as to at least partially cover the second support element,and the first and the second stent-grafts are configured such that thesecond covering element forms the blood-impervious seal with the firstcovering element around the first lateral opening when the secondstent-graft is disposed therethrough, and the first and the secondstent-grafts are in their radially-expanded states.

For some applications, the first perimeter equals at least 250% of thesecond perimeter, such as at least 400% of the second perimeter. Forsome applications, the first perimeter is between 2.5 and 4.5 cm, andthe second perimeter is between 1 and 1.5 cm.

For some applications, when the first stent-graft is unconstrained inits radially-expanded state, a perimeter of the first lateral opening isat least 40% of the first perimeter. For some applications, when thefirst stent-graft is unconstrained in its radially-expanded state, aperimeter of the first lateral opening is at least 60% of the secondperimeter.

For some applications, the second stent-graft is configured totransition, without inverting, from a radially-compressed state to itsradially-expanded state.

For some applications:

the first lateral opening includes a superior first lateral opening andan inferior first lateral opening,

the first stent-graft is shaped so as to define the superior firstlateral opening facing in a first radial direction, and the inferiorfirst lateral opening facing a second radial direction generallyopposite the first radial direction, and

the first and the second stent-grafts are configured such that thesecond stent-graft forms the blood-impervious seal with the firststent-graft around one of the superior and inferior first lateralopenings when the second stent-graft is disposed therethrough, and thefirst and second stent-grafts are in their radially-expanded states.

For some applications, the first and the second stent-grafts areconfigured such that the second stent-graft forms the blood-imperviousseal with the first covering element around the superior first lateralopening when the second stent-graft is disposed therethrough, and thefirst and second stent-grafts are in their radially-expanded states.

For some applications, the first stent-graft is shaped so as to defineexactly one first lateral opening when the first stent-graft is in itsradially-expanded state.

There is still further provided, in accordance with an application ofthe present invention, apparatus including a multi-component stent-graftsystem, which includes:

a first stent-graft, which is shaped so as to define, when in aradially-expanded state, proximal and distal superior first lateralopenings facing in a first radial direction, and a distal inferior firstlateral opening facing a second radial direction generally opposite thefirst radial direction; and

second, third, and fourth branching stent-grafts, which are configuredassume radially-expanded states, wherein the first, the second, thethird, and the fourth stent-grafts are configured such that thebranching stent-grafts form respective blood-impervious seals with thefirst stent-graft around the distal inferior first lateral opening, thedistal superior first lateral opening, and the proximal superior firstlateral opening, respectively, when the branching stent-grafts aredisposed therethrough, respectively, and the first, the second, thethird, and the fourth stent-grafts are in their radially-expandedstates.

For some applications:

the first stent-graft includes a first generally tubular support elementand a first covering element attached to the first support element so asto at least partially cover the first support element, and the firstcovering element and the first support element are shaped so as totogether define, when the first stent-graft is in its radially-expandedstate, the proximal and the distal superior first lateral openingsfacing in the first radial direction, and the distal inferior firstlateral opening facing the second radial direction, and

the second, the third, and the fourth branching stent-grafts includerespective generally tubular branching support elements and respectivebranching covering elements, attached to the branching support elementsso as to at least partially cover the branching support elements, andthe first, the second, the third, and the fourth stent-grafts areconfigured such that the branching covering elements form the respectiveblood-impervious seals with the first covering element around the distalinferior first lateral opening, the distal superior first lateralopening, and the proximal superior first lateral opening, respectively,when the branching stent-grafts are disposed therethrough, respectively,and the first, the second, the third, and the fourth stent-grafts are intheir radially-expanded states.

For some applications, the distal inferior first lateral opening is notaxially aligned with either of the proximal or distal superior firstlateral openings. For some applications, the distal inferior firstlateral opening does not axially overlap with either of the proximal ordistal superior first lateral openings.

There is additionally provided, in accordance with an application of thepresent invention, apparatus including a multi-component stent-graftsystem, which includes:

a first stent-graft, which is shaped so as to define, when in aradially-expanded state, a superior first lateral opening facing in afirst radial direction, and an inferior first lateral opening facing ina second radial direction generally opposite the first radial direction;

a second stent-graft, which is configured to assume a radially-expandedstate, wherein the first and the second stent-grafts are configured suchthat the second stent-graft forms a blood-impervious seal with the firststent-graft around the superior first lateral opening when the secondstent-graft is disposed therethrough, and the first and the secondstent-grafts are in their radially-expanded states;

a third stent-graft, which is shaped so as to define a third lateralopening through the third stent-graft when the third stent-graft is in aradially-expanded state; and

a fourth stent-graft having first and second ends, which stent-graft isconfigured to assume a radially-expanded state, wherein the first, thethird, and the fourth stent-grafts are configured such that, when thefirst, the third, and the fourth stent-grafts are in theirradially-expanded states, the fourth stent-graft forms blood-imperviousseals with (a) the first stent-graft around the inferior first lateralopening when the first end of the fourth stent-graft is disposedtherethrough, and (b) the third stent-graft around the third lateralopening when the second end of the fourth stent-graft is disposedtherethrough.

For some applications:

the first stent-graft includes a first generally tubular support elementand a first covering element attached to the first support element so asto at least partially cover the first support element, and the firstcovering element and the first support element are shaped so as totogether define, when the first stent-graft is in its radially-expandedstate, the superior first lateral opening facing in the first radialdirection, and the inferior first lateral opening facing in the secondradial direction,

the second stent-graft includes a second generally tubular supportelement and a second covering element attached to the second supportelement so as to at least partially cover the second support element,and the first and the second stent-grafts are configured such that thesecond covering element forms the blood-impervious seal with the firstcovering element around the superior first lateral opening when thesecond stent-graft is disposed therethrough, and the first and thesecond stent-grafts are in their radially-expanded states,

the third stent-graft includes a third generally tubular support elementand a third covering element attached to the third support element so asto at least partially cover the third support element, and the thirdcovering element and the third support element are shaped so as totogether define the third lateral opening through the third stent-graftwhen the third stent-graft is in its radially-expanded state, and

the fourth stent-graft includes a fourth generally tubular supportelement and a fourth covering element attached to the fourth supportelement so as to at least partially cover the fourth support element,and the first, the third, and the fourth stent-grafts are configuredsuch that, when the first, the third, and the fourth stent-grafts are intheir radially-expanded states, the fourth covering element forms theblood-impervious seals with (a) the first covering element around theinferior first lateral opening when the first end of the fourthstent-graft is disposed therethrough, and (b) the third covering elementaround the third lateral opening when the second end of the fourthstent-graft is disposed therethrough.

For some applications, the inferior first lateral opening is not axiallyaligned with the superior first lateral opening. For some applications,the inferior first lateral opening does not axially overlap with thesuperior first lateral opening.

There is yet additionally provided, in accordance with an application ofthe present invention, apparatus including a multi-component stent-graftsystem, which includes:

a first stent-graft, which is configured to assume radially-expanded andradially-compressed states;

a second stent-graft, which is configured to assume radially-expandedand radially-compressed states; and

a delivery tool, which includes an outer tube, in which the first andthe second stent-grafts are initially positioned at respective axialsites within the outer tube, in their radially-compressed states withoutbeing fixed to each other.

For some applications, the first and second stent-grafts are initiallypositioned in the outer tube such that at least one end of the firststent-graft is within a distance of a distal end of the outer tube,which distance equals the sum of 2 cm and an axial length of the firststent-graft; and the delivery tool is shaped so as to define first andsecond stopper elements, which are configured and initially positionedto prevent movement of the first and the second stent-grafts,respectively, in a proximal direction away from the distal end of theouter tube. For some applications, an inner surface of the outer tube isshaped so as to define the first and second stopper elements. For someapplications, the delivery tool further includes an inner longitudinalmember, which is initially positioned such that first and secondportions thereof are within the first and the second stent-grafts,respectively, and the inner longitudinal member is shaped so as todefine the first and the second stopper elements. For some applications,the inner longitudinal member is shaped so as to define a lumentherethrough.

For some applications:

the first and the second stent-grafts are initially positioned in theouter tube such that at least one end of the first stent-graft is withina distance of a distal end of the outer tube, which distance equals thesum of 2 cm and an axial length of the first stent-graft,

the delivery tool further includes an inner longitudinal member, whichis initially positioned such that first and second portions thereof arewithin the first and the second stent-grafts, respectively, and

the inner longitudinal member is shaped so as to define a stopperelement, which is:

-   -   configured and initially positioned to prevent movement of the        first stent-graft in a proximal direction away from the distal        end of the outer tube, and    -   configured to be withdrawable in the proximal direction through        the second stent-graft, and after being thus withdrawn, to        prevent movement of the second stent-graft in the proximal        direction.

For some applications, an inner surface of the outer tube is shaped soas to define at least one pusher element, which is configured to preventmovement of at least one of the first and the second stent-grafts in theproximal direction.

For some applications, the delivery tool further includes at least onepusher element, which is configured to prevent movement of at least oneof the first and the second stent-grafts in the proximal direction.

For some applications, the inner longitudinal member is shaped so as todefine a lumen therethrough.

For some applications, the first stent-graft is initially positioned inthe outer tube such that at least one end of the first stent-graft iswithin a distance of a distal end of the outer tube, which distanceequals the sum of 2 cm and an axial length of the first stent-graft, andthe second stent-graft is initially positioned in the outer tube suchthat the first stent-graft is longitudinally between the distal end ofthe outer tube and the second stent-graft.

For some applications, the first stent-graft is shaped so as to define afirst lateral opening. For some applications, the first stent-graftincludes a first generally tubular support element and a first coveringelement, which is attached to the first support element so as to atleast partially cover the first support element, and the first coveringelement and the first support element are shaped so as to togetherdefine the first lateral opening; the second stent-graft includes asecond generally tubular support element and a second covering element,which is attached to the second support element so as to at leastpartially cover the second support element; and the first and the secondstent-grafts are configured such that the second covering element formsa blood-impervious seal with the first covering element around the firstlateral opening when the second stent-graft is disposed therethrough,and the first and the second stent-grafts are in their radially-expandedstates.

For any of the applications described above, when the second stent-graftis disposed through the first lateral opening and the first and thesecond stent-grafts are in their radially-expanded states: a proximalportion of the second support element may be disposed within the firststent-graft, and the second covering element may not fully cover theproximal portion of the second support element, thereby allowing bloodflow through the first stent-graft. For some applications, an axialportion of the proximal portion of the second support element having alength of at least 1 cm has a perimeter that is at least 10% greaterthan a perimeter of a portion of the first stent-graft in which theproximal portion of the second support element is disposed, when thefirst and second stent-grafts are in their radially-expanded states. Forsome applications, the second covering element is configured to cover adistal sub-portion, and not a proximal sub-portion, of the proximalportion of the second support element.

For any of the applications described above, a proximal end of thesecond stent-graft may be flared radially outward in a proximaldirection, when the second stent-graft is in its radially-expandedstate.

For any of the applications described above, a section of the secondcovering element may extend through the first lateral opening and into aportion of the first stent-graft when the second stent-graft is disposedthrough the first lateral opening.

For any of the applications described above, the second stent-graft mayhave a generally cylindrical shape when the second stent-graft isunconstrained in its radially-expanded state.

For any of the applications described above, the first and the secondstent-grafts may be configured for transluminal delivery for transportto respective sites within a body lumen when in theirradially-compressed states. For some applications, the secondstent-graft is adapted for transluminal delivery in itsradially-compressed state through a portion of the first stent-graft andthe first lateral opening, while the first stent-graft is in itsradially-expanded state.

For any of the applications described above, the first covering elementonly partially covers the first support element.

For any of the applications described above, the first stent-graft mayfurther include one or more radiopaque markers, located in a vicinity ofthe first lateral opening.

For any of the applications described above, at least one of the firstand the second support elements may be shaped so as to define one ormore circumferentially-disposed, radially-protruding barbs, when the atleast one of the first and second support elements is in itsradially-expanded state.

For any of the applications described above, an axial length of thefirst stent-graft may be between 5 and 30 cm, when the first stent-graftis unconstrained in its radially-expanded state. For any of theapplications described above, an axial length of the second stent-graftmay be between 5 and 20 cm, when the second stent-graft is unconstrainedin its radially-expanded state. For any of the applications describedabove, a greatest perimeter of the first stent-graft may be between 4.5and 19 cm, when the first stent-graft is unconstrained in itsradially-expanded state. For any of the applications described above, agreatest perimeter of the second stent-graft may be between 9 and 22 cm,when the second stent-graft is unconstrained in its radially-expandedstate.

For any of the applications described above, a perimeter of one end ofthe first stent-graft may be between 7.5 and 15 cm, when the firststent-graft is unconstrained in its radially-expanded state. For any ofthe applications described above, a perimeter of one end of the secondstent-graft may be between 5 and 15.4 cm, when the second stent-graft isunconstrained in its radially-expanded state.

There is also provided, in accordance with an application of the presentinvention, a method for treating a patient, including:

transvascularly introducing and positioning a first stent-graft, whichis shaped so as to define one or more first lateral openings, such that(a) a proximal portion of the first stent-graft, including a proximalend of the first-stent-graft, is in a proximal portion of a main bloodvessel, (b) a distal portion of the first stent-graft, including adistal end of the first stent-graft, is in a branching blood vessel thatbranches from the main blood vessel at a bifurcation, and (c) one of theone or more first lateral openings is disposed within the main bloodvessel facing toward a distal portion of the main blood vessel, whichdistal portion is distal to the bifurcation; and

transvascularly introducing and passing a second stent-graft through theproximal portion of the first stent-graft such that the secondstent-graft is disposed through the first lateral opening and isdisposed partially in the distal portion of the main blood vessel, andforms a blood-impervious seal with the first stent-graft around thefirst lateral opening.

There is further provided, in accordance with an application of thepresent invention, a method for treating a patient, including:

transvascularly introducing and positioning a first stent-graft, whichis shaped so as to define one or more first lateral openings, such that(a) a proximal portion of the first stent-graft, including a proximalend of the first-stent-graft, is in an upper part of a descending aorta,(b) a distal portion of the first stent-graft, including a distal end ofthe first stent-graft, is in a branch of an aortic arch, and (c) one ofthe one or more first lateral openings is disposed within the aorticarch facing upstream, generally toward an ascending aorta; and

transvascularly introducing and passing a second stent-graft through theproximal portion of the first stent-graft such that the secondstent-graft is disposed through the one of the one or more first lateralopenings and is disposed partially in the aortic arch, and forms ablood-impervious seal with the first stent-graft around the one of theone or more first lateral openings.

For some applications, the branch is a left subclavian artery, andpositioning the first stent-graft includes positioning the firststent-graft such that the distal portion of the first stent-graft,including the distal end of the first stent-graft, is in the leftsubclavian artery. For some applications, passing includes passing thesecond stent-graft through the proximal portion of the first stent-graftsuch that the second stent-graft is disposed through the one of the oneor more first lateral openings and is disposed partially in the aorticarch, and a distal portion of the second stent-graft, including a distalend of the second stent-graft, is in a left common carotid artery.

For some applications:

the branch is a brachiocephalic artery,

the first lateral openings include proximal and distal superior firstlateral openings, and a distal inferior first lateral opening,

positioning the first stent-graft includes positioning the firststent-graft such that (a) the distal portion of the first stent-graft,including the distal end of the first stent-graft, is in thebrachiocephalic artery, (b) the distal inferior first lateral openingfaces upstream, generally toward the ascending aorta, and (c) theproximal and the distal superior first lateral openings face and arealigned with a left subclavian artery and a left common carotid artery,respectively, and

passing the second stent-graft includes passing the second stent-graftthrough the proximal portion of the first stent-graft such that thesecond stent-graft is disposed through the distal inferior first lateralopening and is disposed partially in the distal portion of the mainblood vessel.

For some applications, the method further includes transvascularlyintroducing and positioning third and fourth stent-grafts through theproximal portion of the first stent-graft such the third and fourthstent-grafts are disposed through the proximal and the distal superiorfirst lateral openings, respectively, and are disposed partially in theleft subclavian artery and the left common carotid artery, respectively,and form blood-impervious seals with the first stent-graft around theproximal and the distal superior first lateral openings, respectively.

For some applications:

the branch is a left common carotid artery,

the first lateral openings include a superior first lateral opening andan inferior first lateral opening,

positioning the first stent-graft includes positioning the firststent-graft such that (a) the distal portion of the first stent-graft,including the distal end of the first stent-graft, is in the left commoncarotid artery, (b) the inferior first lateral opening faces upstream,generally toward the ascending aorta, and (c) the superior first lateralopening faces and is aligned with a left subclavian artery, and

further including transvascularly introducing a third stent-graft via aright subclavian artery, and positioning the third stent-graft such thata proximal portion of the third stent-graft, including a proximal end ofthe third stent-graft is disposed in a brachiocephalic artery, and adistal portion of the third stent-graft, including a proximal end of thethird-stent graft, is disposed in a portion of at least one blood vesselselected from the group consisting of: the aortic arch, and an upperpart of an ascending aorta, and a third lateral opening defined by thethird stent-graft faces upstream, generally toward the descending aorta,

passing the second stent-graft includes passing the second stent-graftthrough the proximal portion of the first stent-graft such that thesecond stent-graft is disposed through the inferior first lateralopening and the third lateral opening, and is disposed partially in theaortic arch.

For some applications, the method further includes transvascularlyintroducing and positioning a fourth stent-graft through the proximalportion of the first stent-graft such the fourth stent-graft is disposedthrough the superior first lateral opening, and is disposed partially inthe left subclavian artery, and forms a blood-impervious seal with thefirst stent-graft around the superior first lateral opening.

For some applications, transvascularly introducing the first and thesecond stent-grafts includes separately transvascularly introducing thefirst and the second stent-grafts while they are not fixed to oneanother.

For some applications:

transvascularly introducing the first stent-graft includestransvascularly introducing the first stent-graft while in aradially-compressed state, and transitioning the first stent-graft to aradially-expanded state after positioning the first stent-graft,

transvascularly introducing the second stent-graft includestransvascularly introducing the second stent-graft while in aradially-compressed state,

passing the second stent-graft including passing the second stent-graft,while in its radially-compressed state, through the proximal portionafter the first stent-graft has been transitioned to itsradially-expanded state, and

the method further includes, after passing the second stent-graft,transitioning, without inverting, the second stent-graft from aradially-compressed state to a radially-expanded state.

For some applications, transitioning the first stent-graft includestransitioning the first stent-graft to its radially-expanded state inwhich a first perimeter of a first end of the first stent-graft equalsat least 200% of a second perimeter of a second end of the firststent-graft, such as at least 250%, or at least 400%. For someapplications, the first perimeter is between 2.5 and 4.5 cm, and thesecond perimeter is between 1 and 1.5 cm.

For some applications, the method further includes identifying that thepatient suffers from a thoracic aortic aneurysm of an aortic arch, andtransvascularly introducing the first stent-graft includestransvascularly introducing the first stent-graft responsively to theidentifying.

There is still further provided, in accordance with an application ofthe present invention, a method for treating a patient, including:

transvascularly introducing and positioning a first stent intovasculature of the patient;

transvascularly introducing and passing a second stent through a portionof the first stent such that the second stent is disposed through afirst lateral opening defined by the first stent; and

transvascularly introducing and passing a third stent sequentiallythrough (a) the portion of the first stent, (b) the first lateralopening, and (c) a portion of the second stent, such that the thirdstent is disposed through a second lateral opening defined by the secondstent.

For some applications, the first and second stents include respectivefirst and second support elements and respective first and secondcovering elements attached to the first and second support elements,respectively, and passing the second stent includes disposing the secondstent through the first lateral opening such that the second coveringelement forms a blood-impervious seal with the first covering elementaround the first lateral opening.

For some applications, the second and third stents include respectivesecond and third support elements and respective second and thirdcovering elements attached to the second and third support elements,respectively, and passing the third stent includes disposing the thirdstent through the second lateral opening such that the third coveringelement forms a blood-impervious seal with the second covering elementaround the second lateral opening.

For some applications, transvascularly introducing the first, thesecond, and the third stent includes separately transvascularlyintroducing the first, the second, and the third stent while they arenot fixed to one another.

For some applications, passing the third stent includes passing thethird stent while the first and the second stent are inradially-expanded states, and the third stent is in aradially-compressed state.

For some applications, the method further includes transvascularlyintroducing and passing a fourth stent sequentially through (a) theportion of the first stent, (b) the first lateral opening, (c) theportion of the second stent, (d) the second lateral opening, and (e) aportion of the third stent, such that the fourth stent is disposedthrough a third lateral opening defined by the third stent. For someapplications, passing the fourth stent includes passing the fourth stentwhile the first, the second, and the third stent are inradially-expanded states, and the fourth stent is in aradially-compressed state.

For some applications:

positioning the first stent includes positioning the first stent suchthat (a) a proximal portion of the first stent, including a proximal endof the first-stent, is in a proximal portion of a main blood vessel, (b)a distal portion of the first stent, including a distal end of the firststent, is in a branching blood vessel that branches from the main bloodvessel at a bifurcation, and (c) the first lateral opening is disposedwithin the main blood vessel facing toward a distal portion of the mainblood vessel, which distal portion is distal to the bifurcation, and

passing the second stent includes passing the second stent through theportion of the first stent such that the second stent is disposedthrough the first lateral opening and is disposed partially in thedistal portion of the main blood vessel.

For some applications:

the main blood vessel is an aorta, the branching blood vessel is abranch of an aortic arch, and the distal portion of the main body lumenis a portion of the aortic arch,

positioning the first stent includes positioning the first stent suchthat the proximal portion of the first stent, including the proximal endof the first-stent, is in an upper part of a descending aorta, thedistal portion of the first stent, including the distal end of the firststent, is in the branch of the aortic arch, and the first lateralopening faces upstream, generally toward an ascending aorta, and

passing includes passing the second stent through the proximal portionof the first stent such that the second stent is disposed through thefirst lateral opening and is disposed partially in the aortic arch.

For some applications, the branch is a left subclavian artery, andpositioning the first stent includes positioning the first stent suchthat the distal portion of the first stent, including the distal end ofthe first stent, is in the left subclavian artery. For someapplications, passing includes passing the second stent through theproximal portion of the first stent such that the second stent isdisposed through the first lateral opening and is disposed partially inthe aortic arch, and a distal portion of the second stent, including adistal end of the second stent, is in a left common carotid artery.

For some applications:

transvascularly introducing the first stent includes transvascularlyintroducing the first stent while in a radially-compressed state, andtransitioning the first stent to a radially-expanded state afterpositioning the first stent,

transvascularly introducing the second stent includes transvascularlyintroducing the second stent while in a radially-compressed state,

passing the second stent including passing the second stent, while inits radially-compressed state, through the proximal portion after thefirst stent has been transitioned to its radially-expanded state, and

the method further includes, after passing the second stent,transitioning, without inverting, the second stent from aradially-compressed state to a radially-expanded state.

For some applications, transitioning the first stent includestransitioning the first stent to its radially-expanded state in which afirst perimeter of a first end of the first stent equals at least 200%of a second perimeter of a second end of the first stent, such as atleast 250% or at least 400%. For some applications, the first perimeteris between 7.5 and 15 cm, and the second perimeter is between 2.5 and5.7 cm.

For some applications, the method further includes identifying that thepatient suffers from a thoracic aortic aneurysm of an aortic arch, andtransvascularly introducing the first stent includes transvascularlyintroducing the first stent responsively to the identifying.

There is additionally provided, in accordance with an application of thepresent invention, a method including:

transvascularly introducing, into vasculature of a patient, a deliverytool, which includes an outer tube, in which first and second stents areinitially positioned at respective axial sites within the outer tube, inradially-compressed states without being fixed to each other;

deploying the first stent from a distal end of the outer tube, such thatthe first stent transitions to a radially-expanded state; and

after the first stent transitions to the radially-expanded state,deploying the second stent from the distal end of the outer tube, suchthat the second stent transitions to a radially-expanded state.

For some applications:

the delivery tool is shaped so as to define first and second stopperelements, which are configured and initially positioned to preventmovement of the first and second stents, respectively, in a proximaldirection away from the distal end of the outer tube,

deploying the first stent includes withdrawing, in the proximaldirection, the outer tube, such that the first stopper element preventsthe movement of the first stent in the proximal direction, and

deploying the second stent includes withdrawing the outer tube in theproximal direction, such that the second stopper element prevents themovement of the second stent in the proximal direction.

For some applications, an inner surface of the outer tube is shaped soas to define the first and second stopper elements.

For some applications, the delivery tool further includes an innerlongitudinal member, which is initially positioned such that first andsecond portions thereof are within the first and second stents,respectively, and the inner longitudinal member is shaped so as todefine the first and second stopper elements.

For some applications:

the delivery tool further includes an inner longitudinal member, whichis initially positioned such that first and second portions thereof arewithin the first and second stents, respectively,

the inner longitudinal member is shaped so as to define a stopperelement, which is (a) configured and initially positioned to preventmovement of the first stent in a proximal direction away from the distalend of the outer tube, and (b) configured to be withdrawable in theproximal direction through the second stent, and after being thuswithdrawn, to prevent movement of the second stent in the proximaldirection,

deploying the first stent includes withdrawing the outer tube in theproximal direction, such that the stopper element prevents the movementof the first stent in the proximal direction, and

deploying the second stent includes:

-   -   withdrawing the inner longitudinal member in the proximal        direction, such that the stopper element passes through the        second stent; and    -   withdrawing the outer tube in the proximal direction, such that        the stopper element prevents the movement of the second stent in        the proximal direction.

There is yet additionally provided, in accordance with an application ofthe present invention, a method for treating a patient, including:

transvascularly introducing a stent-graft into vasculature of thepatient; and

positioning the stent-graft such that (a) a proximal portion of thestent-graft, including a proximal end of the first-stent-graft, is in abrachiocephalic artery, (b) a distal portion of the stent-graft,including a distal end of the stent-graft, is disposed in a portion ofat least one blood vessel selected from the group consisting of: anaortic arch, and an upper part of an ascending aorta, and (c) a lateralopening defined by the stent-graft is disposed in the aortic arch facinggenerally toward a descending aorta.

For some applications, the stent-graft is a first stent-graft, andfurther including transvascularly introducing and positioning a secondstent-graft through the lateral opening, such that the secondstent-graft forms a blood-impervious seal with the first stent-graftaround the lateral opening.

There is also provided, in accordance with an application of the presentinvention, a method for assembling a multi-component stent-graft system,the method including:

providing (a) a first generally tubular stent-graft, which is shaped soas to define a first lateral opening when the first stent-graft is in aradially-expanded state, (b) a second generally tubular stent-graft,which is shaped so as to define a second lateral opening when the secondstent-graft is in a radially-expanded state, and (c) a third generallytubular stent-graft;

while the first stent-graft is in its radially-expanded state and thesecond stent-graft is in a radially-compressed state, disposing thesecond stent-graft through the first lateral opening, and causing thesecond stent-graft to transition to its radially-expanded state, suchthat the second stent-graft forms a blood-impervious seal with the firststent-graft around the first lateral opening; and

while the second stent-graft is in its radially-expanded state and thethird stent-graft is in a radially-compressed state, disposing the thirdstent-graft through the second lateral opening, and causing the thirdstent-graft to transition to a radially-expanded state, such that thethird stent-graft forms a blood-impervious seal with the secondstent-graft around the second lateral opening.

For some applications, the third stent-graft is shaped so as to define athird lateral opening when in its radially-expanded state, and themethod further includes:

providing a fourth generally tubular stent-graft; and

while the third stent-graft is in its radially-expanded state and thefourth stent-graft is in a radially-compressed state, disposing thefourth stent-graft through the third lateral opening, and causing thefourth stent-graft to transition to a radially-expanded state, such thatthe fourth stent-graft forms a blood-impervious seal with the thirdstent-graft around the third lateral opening.

There is further provided, in accordance with an application of thepresent invention, a method for assembling a multi-component stent-graftsystem, the method including:

providing (a) a first generally tubular stent-graft, which, whenunconstrained in a radially-expanded state: (i) defines a first lateralopening, and (ii) has a first perimeter of a first end thereof thatequals at least 200% of a second perimeter of a second end thereof, and(b) a second generally tubular stent-graft; and

while the first stent-graft is in its radially-expanded state and thesecond stent-graft is in a radially-compressed state, disposing thesecond stent-graft through the first lateral opening, and causing thesecond stent-graft to transition to a radially-expanded state, such thatthe second stent-graft forms a blood-impervious seal with the firststent-graft around the first lateral opening.

There is still further provided, in accordance with an application ofthe present invention, a method for assembling a multi-componentstent-graft system, the method including:

providing (a) a first stent-graft, which is shaped so as to define, whenin a radially-expanded state, proximal and distal superior first lateralopenings facing in a first radial direction, and a distal inferior firstlateral opening facing a second radial direction generally opposite thefirst radial direction, and (b) second, third, and fourth branchingstent-grafts; and

while the first stent-graft is in its radially-expanded state and thesecond stent-graft is in a radially-compressed state, disposing thesecond stent-graft through the distal inferior first lateral opening,and causing the second stent-graft to transition to a radially-expandedstate, such that the second stent-graft forms a blood-impervious sealwith the first stent-graft around the distal inferior first lateralopening;

while the first stent-graft is in its radially-expanded state and thethird stent-graft is in a radially-compressed state, disposing the thirdstent-graft through the distal superior first lateral opening, andcausing the third stent-graft to transition to a radially-expandedstate, such that the third stent-graft forms a blood-impervious sealwith the first stent-graft around the distal superior first lateralopening; and

while the first stent-graft is in its radially-expanded state and thefourth stent-graft is in a radially-compressed state, disposing thefourth stent-graft through the proximal superior first lateral opening,and causing the fourth stent-graft to transition to a radially-expandedstate, such that the fourth stent-graft forms a blood-impervious sealwith the first stent-graft around the proximal superior first lateralopening.

There is additionally provided, in accordance with an application of thepresent invention, a method for assembling a multi-component stent-graftsystem, the method including:

providing (a) a first stent-graft, which is shaped so as to define, whenin a radially-expanded state, a superior first lateral opening facing ina first radial direction, and an inferior first lateral opening facingin a second radial direction generally opposite the first radialdirection, (b) a second stent-graft, (c) a third stent-graft, which isshaped so as to define a third lateral opening through the thirdstent-graft when the third stent-graft is in a radially-expanded state,and (d) a fourth stent-graft;

while the first stent-graft is in its radially-expanded state and thesecond stent-graft is in a radially-compressed state, disposing thesecond stent-graft through the superior first lateral opening, andcausing the second stent-graft to transition to a radially-expandedstate, such that the second stent-graft forms a blood-impervious sealwith the first stent-graft around the superior first lateral opening;and

while the first and the third stent-grafts are in theirradially-expanded states and the fourth stent-graft is in aradially-compressed state, disposing first and second ends of the fourthstent-graft through the inferior first lateral opening and the thirdlateral opening, respectively, and causing the fourth stent-graft totransition to a radially-expanded state, such that the fourthstent-graft forms blood-impervious seals with the first stent-graftaround the inferior first lateral opening and the third stent-graftaround the third lateral opening.

The present invention will be more fully understood from the followingdetailed description of embodiments thereof, taken together with thedrawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-C are schematic illustrations of a multi-component stent-graftsystem, in accordance with respective applications of the presentinvention;

FIG. 2 is a schematic illustration of the multi-component stent-graftsystem of FIG. 1-C in an assembled state, in accordance with anapplication of the present invention;

FIGS. 3A-L are schematic illustrations of an exemplary transluminaldelivery procedure for implanting the multi-component stent-graft systemof FIGS. 1A, 1B, 1C, and/or 2, in accordance with an application of thepresent invention;

FIG. 4 is a schematic illustration of another configuration of themulti-component stent-graft system of FIGS. 1A-C and 2, in accordancewith an application of the present invention;

FIG. 5 is a schematic illustration of the multi-component stent-graftsystem of FIG. 4 in an assembled state, in accordance with anapplication of the present invention;

FIGS. 6A-H are schematic illustrations of an exemplary transluminaldelivery procedure for implanting the multi-component stent-graft systemof FIGS. 4 and 5, in accordance with an application of the presentinvention;

FIG. 7 is a schematic illustration of another configuration of themulti-component stent-graft system of FIGS. 1A-C and 2, in accordancewith an application of the present invention;

FIG. 8 is a schematic illustration of multi-component stent-graft systemof FIG. 7 in an assembled state, in accordance with an application ofthe present invention;

FIGS. 9A-G are schematic illustrations of an exemplary transluminaldelivery procedure for implanting the multi-component stent-graft systemof FIGS. 7 and 8, in accordance with an application of the presentinvention;

FIG. 9H is a schematic illustration of an alternative configuration anddeployment of a multi-component stent-graft system, in accordance withan application of the present invention;

FIG. 10 is a schematic illustration of first and second stent-graftsinitially positioned within an outer tube of a delivery tool, inaccordance with an application of the present invention;

FIGS. 11A-E are schematic illustrations showing the deployment of thefirst and second stent-grafts using the deployment tool of FIG. 10, inaccordance with an application of the present invention; and

FIGS. 12A-C are schematic illustrations of another configuration of thedelivery tool of FIG. 10, in accordance with an application of thepresent invention.

DETAILED DESCRIPTION OF APPLICATIONS

In some applications of the present invention, a multi-componentstent-graft system 10 is provided for treating a thoracic aorticaneurysm 110, such as of the aortic arch. The system is configured to bedeployed in the thoracic aorta and in one or more of the branches of theaortic arch (the brachiocephalic artery, the left common carotid artery,and/or the left subclavian artery).

The multi-component stent-graft system is configured to be deployed in astraightforward procedure that readily accommodates ordinary anatomicalvariances among different patients. For example, the locations ofbifurcations of the three branches of the aortic arch vary amongpatients. The stent-grafts of the system are assembled in situ toaccommodate the dimensions of the particular patient's anatomy,generally without requiring prior customization of the stent-grafts orin situ modifications to the stent-grafts, which might be expensiveand/or complex.

Typically, upon deployment, the multi-component stent-graft systemdefines a blood-flow path from the ascending aorta, over the aorticarch, and to the descending aorta. The multi-component stent-graftsystem additionally provides blood-flow paths to the three branches ofthe aortic arch.

The multi-component stent-graft system may have various configurations,and may be deployed in various combinations and subsets of the aorticarch, ascending aorta, descending aorta, and three branches of theaortic arch. Hereinbelow are described three exemplary high-levelconfigurations of the stent-graft system, each of which includesnumerous sub-configurations. For the sake of convenience, and withoutlimiting the features of these configurations, the three exemplaryconfigurations are referred to hereinbelow as: (1) a “first stent-grafthaving a single lateral opening,” (2) a “first stent-graft having threelateral openings,” and (3) a “first stent-graft having two lateralopenings.”

First Stent-Graft Having a Single Lateral Opening

FIGS. 1A-C are schematic illustrations of multi-component stent-graftsystem 10, in accordance with respective applications of the presentinvention. In these applications, multi-component stent-graft system 10comprises (a) a first stent-graft 20, (b) a second stent-graft 22, (c)optionally, a third stent-graft 24, and (d) optionally, a fourthstent-graft 26. The stent-grafts are configured to assumeradially-compressed states, such as when initially positioned in one ormore outer tubes of one or more delivery tools, as described hereinbelowwith reference to FIGS. 3B, 3E, 3H, and 3K, and to assumeradially-expanded states upon being deployed from the outer tube(s), asdescribed hereinbelow with reference to FIGS. 3C, 3F, 3I, and 3L. FIGS.1A-C show the stent-grafts in their radially-expanded states. For someapplications, the stent-grafts are relaxed in their radially-expandedstates. For some applications, the stent-grafts are configured to beself-expanding. For example, they may be heat-set to assume theirradially-expanded states.

The First Stent-Graft

First stent-graft 20 typically comprises a first generally tubularsupport element 30 and a first covering element 32 attached to the firstsupport element so as to at least partially cover (e.g., only partiallycover) the first support element. Support element 30 typically comprisesa plurality of structural stent elements. For some applications, atleast some of, e.g., all of, the structural stent elements areinterconnected (as shown in the figures), while for other applications,at least a portion of, e.g., all, of the structural stent elements arenot interconnected (configuration not shown). For some applications,support element 30, as well as support elements 40, 50, and 60, whichare described hereinbelow, comprise a super-elastic alloy, such asNitinol. Covering element 32 serves as a blood flow guide through atleast a portion of the first stent-graft. Each of covering element 32,as well as covering elements 42, 52, and 62, which are describedhereinbelow, typically comprises at least one biologically-compatiblesubstantially blood-impervious flexible sheet, which is attached (suchas by stitching) to at least a portion of the respective supportelement, on either side of the surfaces defined by the support element.The flexible sheet may comprise, for example, a polymeric material(e.g., a polyester, or polytetrafluoroethylene), a textile material(e.g., polyethylene terephthalate (PET)), natural tissue (e.g.,saphenous vein or collagen), or a combination thereof.

First covering element 32 and first support element 30 are shaped so asto together define a first lateral opening 34 through first stent-graft20 when the first stent-graft is in its radially-expanded state. Forsome applications, the first covering element and first support elementare shaped so as to together define exactly one first lateral opening,as shown in FIGS. 1A-C. For other applications, the first coveringelement and first support element are shaped so as to together definemore than one first lateral opening, such as exactly three lateralopenings or exactly two lateral openings, as described hereinbelow withreference to FIGS. 4-5 and 6-7, respectively, or more than three lateralopenings (configuration not shown).

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, i.e., no forces are applied to the stent-graftby a delivery tool, walls of a blood vessel, or otherwise, a firstperimeter P1 of a first (proximal) end 36 of the first stent-graft isgreater than a second perimeter P2 of a second (distal) end 38 of thefirst stent-graft, and/or a first cross-sectional area of the first end36 is greater than a second cross-sectional area of second end 38. Forapplications in which first stent-graft 20 is generally cylindrical whenunconstrained in its radially-expanded state, first and secondperimeters P1 and P2 are first and second diameters. For example, firstperimeter P1 may equal at least 150% of second perimeter P2, such as atleast 200%, at least 250%, at least 300%, or at least 400%, and/or thefirst cross-sectional area may equal at least 225% of the secondcross-sectional area, such as at least 400%, at least 625%, at least900%, or at least 1600%. For some applications, a proximal axial quarterof first-stent graft 20 includes a portion of the stent-graft extendingfrom first proximal end 36 along 25% of an axial length of thestent-graft, and a distal axial quarter of the first stent-graftincludes a portion of the stent-graft extending from second distal end38 along 25% of the axial length of the stent-graft. For someapplications, an average perimeter of the proximal axial quarter equalsat least 150% of an average perimeter of the distal axial quarter, suchas at least 200%, at least 250%, at least 300%, or at least 400%.

For example, first perimeter P1 may be at least 7.5 cm, no more than 15cm, and/or between 7.5 and 15 cm, such as at least 9 cm, no more than 13cm, and/or between 9 and 13 cm, and second perimeter P2 may be at least2.5 cm, no more than 5.7 cm, and/or between 2.5 and 5.7 cm, such as atleast 3 cm, no more than 4.5 cm, and/or between 3 and 4.5 cm.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, a perimeter of first lateral opening 34 is atleast 4.5 cm, no more than 14 cm, and/or between 4.5 and 14 cm, such asat least 6 cm, no more than 12.5 cm, and/or between 6 and 12.5 cm.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, a perimeter of first lateral opening 34 is atleast 30%, e.g., at least 40%, or at least 75% of first perimeter P1,and/or at least 83%, e.g., at least 100%, or at least 200% of secondperimeter P2. For some applications in which first perimeter P1 does notequal second perimeter P2, the perimeter of first lateral opening 34 isat least 60% of the lesser of first and second perimeters P1 and P2.

For some applications, first stent-graft 20, when unconstrained in itsradially-expanded state, has an axial length of at least 5 cm, no morethan 40 cm, and/or between 5 and 30 cm, such as at least 10 cm, no morethan 30 cm, and/or between 10 and 30 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved, as describedhereinbelow with reference to FIG. 1B.) For some applications, firststent-graft 20, when unconstrained in its radially-expanded state, has agreatest perimeter (at any axial location along the stent-graft) of atleast 4.5 cm, no more than 19 cm, and/or between 4.5 and 19 cm, such asat least 12.5 cm, no more than 16 cm, and/or between 12.5 and 16 cm.

For some applications, such dimensions allow the first stent-graft to bepositioned such that (a) a proximal, radially larger, portion of thestent-graft, including proximal end 36 thereof, is disposed in the aortadownstream from the bifurcation with the left subclavian artery, atleast partially in the upper part of the descending aorta, and (b) adistal, radially smaller, portion of the stent-graft, including distalend 38 thereof, is disposed in the left subclavian artery, such asdescribed hereinbelow with reference to FIG. 3C. For some applications,the proximal portion of the stent-graft has an average perimeter that isgreater than (e.g., between 5% and 15% greater than) an averageperimeter of the portion of the aorta in which it is disposed (excludingexpansion of the aorta due to the aneurysm, i.e., assuming the aortawere healthy). For some applications, the distal portion of thestent-graft has an average perimeter that is greater than (e.g., between5% and 15% greater than) the average perimeter of the portion of theleft subclavian artery in which it is disposed.

The Second Stent-Graft

Second stent-graft 22 typically comprises a second generally tubularsupport element 40 and a second covering element 42 attached to thesecond support element so as to at least partially cover the secondsupport element. Support element 40 typically comprises a plurality ofstructural stent elements. For some applications, at least some of,e.g., all of, the structural stent elements are interconnected (as shownin the figures), while for other applications, at least a portion of,e.g., all, of the structural stent elements are not interconnected(configuration not shown). Covering element 42 serves as a blood flowguide through at least a portion of the second stent-graft.

For applications in which multi-component stent-graft system 10 furthercomprises third stent-graft 24, second covering element 42 and secondsupport element 40 are typically shaped so as to together define asecond lateral opening 44 through second stent-graft 22 when the secondstent-graft is in its radially-expanded state. The second stent-graft istypically configured to transition, without inverting, from itsradially-compressed state to its radially-expanded state, typically uponbeing deployed from an outer tube of a deployment tool, such asdescribed hereinbelow with reference to FIG. 3F.

For some applications, when second stent-graft 22 is unconstrained inits radially-expanded state, i.e., no forces are applied to thestent-graft by a delivery tool, walls of a blood vessel, or otherwise, athird perimeter P3 of a first (proximal) end 46 of the secondstent-graft may be at least 5 cm, no more than 15.4 cm, and/or between 5and 15.4 cm, and a fourth perimeter P4 of a second (distal) end 48 ofthe second stent-graft may be at least 2.5 cm, no more than 5.7 cm,and/or between 2.5 and 5.7 cm. For applications in which secondstent-graft 22 is generally cylindrical when unconstrained in itsradially-expanded state, third and fourth perimeters P3 and P4 are thirdand fourth diameters. For some applications, third and fourth perimetersP3 and P4 are equal.

For some applications, when second stent-graft 22 is unconstrained inits radially-expanded state, a perimeter of second lateral opening 44 isat least 4.5 cm, no more than 14 cm, and/or between 4.5 and 14 cm, suchas at least 6 cm, no more than 12.5 cm, and/or between 6 and 12.5 cm.

For some applications, second stent-graft 22, when unconstrained in itsradially-expanded state, has an axial length of at least 5 cm, no morethan 20 cm, and/or between 5 and 20 cm, such as at least 8 cm, no morethan 15 cm, and/or between 8 and 15 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved, as describedhereinbelow with reference to FIG. 1B.) For some applications, secondstent-graft 22, when unconstrained in its radially-expanded state, has agreatest perimeter (at any axial location along the stent-graft) of atleast 9 cm, no more than 22 cm, and/or between 9 and 22 cm, and/or atleast 12 cm, no more than 19 cm, and/or between 12 and 19 cm.

For some applications, such dimensions allow the second stent-graft tobe positioned such that (a) a proximal portion of the stent-graft isdisposed within the lateral opening 34 of the first stent-graft, and (b)a distal portion of the stent-graft, including distal end 48 thereof, isdisposed in a left common carotid artery, such as described hereinbelowwith reference to FIG. 3F. For some applications, the proximal portionof the stent-graft has an average perimeter that is less than (e.g.,between 40% and 70% less than) an average perimeter of the portion ofthe aortic arch in which it is disposed (excluding expansion of theaortic arch due to the aneurysm, i.e., assuming the aortic arch werehealthy). For some applications, the distal portion of the stent-grafthas an average perimeter that is greater than (e.g., between 5% and 15%greater than) the average perimeter of the portion of the left commoncarotid artery in which it is disposed.

The Third Stent-Graft

For applications in which multi-component stent-graft system 10 furthercomprises third stent-graft 24, the third stent-graft typicallycomprises a third generally tubular support element 50 and a thirdcovering element 52 attached to the third support element so as to atleast partially cover the third support element. Support element 50typically comprises a plurality of structural stent elements. For someapplications, at least some of, e.g., all of, the structural stentelements are interconnected (as shown in the figures), while for otherapplications, at least a portion of, e.g., all, of the structural stentelements are not interconnected (configuration not shown). Coveringelement 52 serves as a blood flow guide through at least a portion ofthe third stent-graft.

For applications in which multi-component stent-graft system 10 furthercomprises fourth stent-graft 26, third covering element 52 and thirdsupport element 50 are typically shaped so as to together define a thirdlateral opening 54 through third stent-graft 24 when the thirdstent-graft is in its radially-expanded state. The third stent-graft istypically configured to transition, without inverting, from itsradially-compressed state to its radially-expanded state, typically uponbeing deployed from an outer tube of a deployment tool, such asdescribed hereinbelow with reference to FIG. 3I.

For some applications, when third stent-graft 24 is unconstrained in itsradially-expanded state, i.e., no forces are applied to the stent-graftby a delivery tool, walls of a blood vessel, or otherwise, a fifthperimeter P5 of a first end 56 of the third stent-graft may be at least5.5 cm, no more than 17 cm, and/or between 5.5 and 17 cm, and a sixthperimeter P6 of a second end 58 of the third stent-graft may be at least2.75 cm, no more than 6.3 cm, and/or between 2.75 and 6.3 cm. Forapplications in which third stent-graft 24 is generally cylindrical whenunconstrained in its radially-expanded state, fifth and sixth perimetersP5 and P6 are fifth and sixth diameters. For some applications, fifthand sixth perimeters P5 and P6 are equal.

For some applications, when third stent-graft 24 is unconstrained in itsradially-expanded state, a perimeter of third lateral opening 54 is atleast 4.5 cm, no more than 14 cm, and/or between 4.5 and 14 cm, such asat least 4.5 cm, no more than 12 cm, and/or between 4.5 and 12 cm.

For some applications, third stent-graft 24, when unconstrained in itsradially-expanded state, has an axial length of at least 8.8 cm, or morethan 16.5 cm, and/or between 8.8 and 16.5 cm. (The axial length ismeasured along a central longitudinal axis of the stent-graft, includingin applications in which the stent-graft is curved, as describedhereinbelow with reference to FIG. 1B.) For some applications, thirdstent-graft 24, when unconstrained in its radially-expanded state, has agreatest perimeter (at any axial location along the stent-graft) of atleast 4.4 cm, no more than 7.7 cm, and/or between 4.4 and 7.7 cm, suchas at least 3.3 cm, no more than 6.6 cm, and/or between 3.3 and 6.6 cm.

For some applications, such dimensions allow the third stent-graft to bepositioned such that (a) a proximal portion of the stent-graft isdisposed in the aortic arch, and (b) a distal portion of thestent-graft, including distal end 58 thereof, is disposed in abrachiocephalic artery, such as described hereinbelow with reference toFIG. 3I. For some applications, the proximal portion of the stent-grafthas an average perimeter that is less than (e.g., between 40% and 70%less than) an average perimeter of the portion of the aortic arch inwhich it is disposed (excluding expansion of the aortic arch due to theaneurysm, i.e., assuming the aortic arch were healthy). For someapplications, the distal portion of the stent-graft has an averageperimeter that is greater than (e.g., between 5% and 15% greater than)the average perimeter of the portion of the brachiocephalic artery inwhich it is disposed.

The Fourth Stent-Graft

For applications in which multi-component stent-graft system 10 furthercomprises fourth stent-graft 26, the fourth stent-graft typicallycomprises a fourth generally tubular support element 60 and a thirdcovering element 62 attached to the fourth support element so as to atleast partially cover the fourth support element. Support element 60typically comprises a plurality of structural stent elements. For someapplications, at least some of, e.g., all of, the structural stentelements are interconnected (as shown in the figures), while for otherapplications, at least a portion of, e.g., all, of the structural stentelements are not interconnected (configuration not shown). Coveringelement 62 serves as a blood flow guide through at least a portion ofthe fourth stent-graft.

For some applications, fourth covering element 62 and fourth supportelement 60 are not shaped so as to together define any lateral openingsthrough the fourth stent-graft when the fourth stent-graft is in itsradially-expanded state.

For some applications, when fourth stent-graft 26 is unconstrained inits radially-expanded state, i.e., no forces are applied to thestent-graft by a delivery tool, walls of a blood vessel, or otherwise, aseventh perimeter P7 of a first (proximal) end 66 of the fourthstent-graft may be at least 3 cm, no more than 7 cm, and/or between 3and 7 cm, and a eighth perimeter P8 of a second (distal) end 68 of thefourth stent-graft may be at least 6 cm, no more than 19 cm, and/orbetween 6 and 19 cm. For applications in which fourth stent-graft 26 isgenerally cylindrical when unconstrained in its radially-expanded state,seventh and eighth perimeters P7 and P8 are seventh and eighthdiameters. For some applications, seventh and eighth perimeters P7 andP8 are equal.

For some applications, fourth stent-graft 26, when unconstrained in itsradially-expanded state, has an axial length of at least 9.7 cm, no morethan 18 cm, and/or between 9.7 and 18 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved, as describedhereinbelow with reference to FIG. 1B.) For some applications, fourthstent-graft 26, when unconstrained in its radially-expanded state, has agreatest perimeter (at any axial location along the stent-graft) of atleast 4.8 cm, no more than 8.5 cm, and/or between 4.8 and 8.5 cm, and/orbetween 3.6 and 7.3 cm.

For some applications, such dimensions allow the fourth stent-graft tobe positioned in the aortic arch and/or the upper end of an ascendingaorta, such as described hereinbelow with reference to FIG. 3L. For someapplications, the proximal portion of the stent-graft has an averageperimeter that is less than (e.g., between 40% and 70% greater than) anaverage perimeter of the portion of the aorta in which it is disposed(excluding expansion of the aorta due to the aneurysm, i.e., assumingthe aorta were healthy).

Additional Configuration Detail

Typically, first and second stent-grafts 20 and 22 are not fixed to oneother when they are in their radially-compressed states. Likewise, whenthird stent-graft 24 is provided, first, second, and third stent-grafts20, 22, and 24 are typically not fixed to one other when they are intheir radially-compressed states. Furthermore, when third and fourthstent-grafts 24 and 26 are provided, first, second, third, and fourthstent-grafts 20, 22, 24, and 26 are typically not fixed to one otherwhen they are in their radially-compressed states. In other words, thestent-grafts are initially provided as separate, non-connectedcomponents, as shown in FIGS. 1A-C (although they are typicallyinitially positioned in outer tube(s) of delivery tool(s), as describedhereinbelow), which are typically assembled in situ. Typically, firstand second covering element 32 and 42 are not fixed to one other whenthey are in their radially-compressed states. Likewise, when thirdstent-graft 24 is provided, first, second, and third covering element32, 42, and 52 are typically not fixed to one other when first, second,and third stent-grafts 20, 22, and 24 are in their radially-compressedstates. Furthermore, when third and fourth stent-grafts 24 and 26 areprovided, first, second, third, and fourth covering elements 32, 42, 52,and 62 are typically not fixed to one other when first, second, third,and fourth stent-grafts 20, 22, 24, and 26 are in theirradially-compressed states.

Reference is still made to FIGS. 1A-C. In the configurations shown inFIGS. 1A and 1C, stent-grafts 20, 22, 24, and 26 are configured (e.g.,heat-set) to have generally straight longitudinal axes whenunconstrained in their radially-expanded states, i.e., no forces areapplied to the stent-grafts by a delivery tool, walls of a blood vessel,or otherwise. The stent-grafts typically assumed curved shapes whenplaced in respective blood vessels because of the force applied to thestent-grafts by the walls of the blood vessels, such as shown in FIGS.3A-L.

In the configuration shown in FIG. 1B, stent-grafts 20, 22, 24, and 26are configured (e.g., heat-set) to have generally curved longitudinalaxes when unconstrained in their radially-expanded states, i.e., noforces are applied to the stent-grafts by a delivery tool, walls of ablood vessel, or otherwise. This curvature may help properly positionthe stent-grafts with respect to one another, such as shown in FIGS. 2and 3A-L. For some applications in which the stent-grafts are curved,first lateral openings 34, second lateral openings 44, and/or thirdlateral opening 54 are positioned on outer portions of the curves, asshown in FIG. 1B.

For some applications, at least one the stent-grafts is generallystraight, as shown in FIG. 1A, while at least another one of thestent-grafts is generally curved, as shown in FIG. 1B.

For some applications, such as in the configurations shown in FIGS. 1Aand 1B, the respective covering element 42, 52, and/or 62 of one or moreof second, third, and fourth stent-grafts 22, 24, and 26 does not fullycover a proximal sub-portion 70 of the support element, thereby allowingblood flow through the stent-graft, as described hereinbelow withreference to FIG. 2. Optionally, one or more of proximal sub-portions 70is flared radially outward in a proximal direction at their proximalends.

For some applications, such as in the configurations shown in FIG. 1C,one or more of proximal ends 46, 56, and 66 of second, third, and fourthstent-grafts 22, 24, and 26 are outwardly flared in a proximal directionwhen the stent-grafts are unconstrained in their radially-expandedstates, i.e., no forces are applied to the stent-grafts by a deliverytool, walls of a blood vessel, or otherwise. Optionally, thestent-grafts are additionally slightly indented radially inwardimmediately distal to the outward flares. Typically, covering elements42, 52, and 62 cover at least a distal portion of the outward flares.The flares enable secure anchoring of the stent-grafts to one another,such as described hereinbelow with reference to FIGS. 2 and 3F-L. Theflared portions (together with radially-indented portions) may serve asinterface members, and may generally have the shape of an hourglass. Theradially-indented (narrower) portions may be sized to be firmly coupledwith a lateral opening of another stent-graft.

For some applications, one or more of the stents both define a flare, asshown in FIG. 1C, and are curved, as shown in FIG. 1B. Alternatively oradditionally, for some applications, at least one the stent-graftsdefines a flare, as shown in FIG. 1C, while at least another one of thestent-grafts does not define a flare, as shown in FIGS. 1A-B.

For some applications, one or more (e.g., all) of the lateral openingsare circumscribed by respective generally annular structural stentelements of the support elements.

Assembly of the Stent-Grafts

FIG. 2 is a schematic illustration of multi-component stent-graft system10, having the configurations shown in FIG. 1-C, in an assembled state,in accordance with an application of the present invention. As mentionedabove, such assembly is typically performed in situ during animplantation procedure, but such assembly may also be performed ex vivo.First, second, third, and fourth stent-grafts 20, 22, 24, and 26 areshown in FIG. 2 in their radially-expanded states. Second stent-graft 22is configured to be disposed through first lateral opening 34, such thata portion of the second stent-graft is disposed within first stent-graft20, and a portion of the second stent-graft is disposed outside of thefirst stent-graft. The first and second stent-grafts are configured suchthat second covering element 42 forms a blood-impervious seal with firstcovering element 32 around first lateral opening 34, when the secondstent-graft is thus disposed through the first lateral opening, andfirst and second stent-grafts 20 and 22 are in their radially-expandedstates. The first and second stent-grafts are securely anchored to eachother. The blood-impervious seal is typically formed because supportelement 30 of the first stent-graft is configured to having a restingperimeter that is greater than the perimeter of the first lateralopening, such that the first lateral opening squeezes the firststent-graft when the first stent-graft expands.

For some applications, when second stent-graft 22 is disposed throughfirst lateral opening 34 and first and second stent-grafts 20 and 22 arein their radially-expanded states, a proximal portion 82 of secondsupport element 40 is disposed within first stent-graft 20, and secondcovering element 42 does not fully cover proximal portion 82, therebyallowing blood flow through the first stent-graft (i.e., the secondcovering element does not fully cover proximal sub-portion 70).(Optionally, proximal sub-portion 70 is flared radially outward in aproximal direction at its proximal end.) Typically, at least adistal-most portion of proximal portion 82 is covered by second coveringelement 42, in order to form the above-mentioned blood-impervious sealwith first covering element 32. Thus, second covering element 42 may beconfigured to cover a distal sub-portion, and not a proximalsub-portion, of proximal portion 82.

For some applications, such as for the configurations shown in FIGS.1A-B, second support element 40 is configured to extend into firststent-graft 20 a distance sufficient to help anchor the secondstent-graft to the first stent-graft, such as at least 4 cm, no morethan 10 cm, and/or between 4 and 10 cm. For some applications, proximalportion 82 has a perimeter that is sufficient to apply aradially-outward force against an inner surface of a wall of firststent-graft 20, in order to help anchor the second stent-graft to thefirst stent-graft. For example, an axial portion of proximal portion 82having a length of at least 1 cm may have a perimeter that is at least10% greater than a perimeter of a portion of the first stent-graft inwhich proximal portion 82 is disposed. Typically, second stent-graft 22is deployed such that proximal portion 82 extends into the firststent-graft in a proximal direction from first lateral opening 34, asshown in FIG. 2.

For applications in which third stent-graft 24 is provided, the thirdstent-graft is configured to be disposed through second lateral opening44, such that a portion of the third stent-graft is disposed withinsecond stent-graft 22 (and, optionally, depending on the length of theportion, also within first stent-graft 20), and a portion of the thirdstent-graft is disposed outside of the second stent-graft. The secondand third stent-grafts are configured such that third covering element52 forms a blood-impervious seal with second covering element 42 aroundsecond lateral opening 44, when the third stent-graft is thus disposedthrough the second lateral opening, and second and third stent-grafts 22and 24 are in their radially-expanded states. The second and thirdstent-grafts are securely anchored to each other.

For some applications, when third stent-graft 24 is disposed throughsecond lateral opening 44 and second and third stent-grafts 22 and 24are in their radially-expanded states, a proximal portion 92 of thirdsupport element 50 is disposed within second stent-graft 22, and thirdcovering element 52 does not fully cover proximal portion 92, therebyallowing blood flow through the second stent-graft (i.e., the thirdcovering element does not fully cover proximal sub-portion 70).(Optionally, proximal sub-portion 70 is flared radially outward in aproximal direction at its proximal end.) Typically, at least adistal-most portion of proximal portion 92 is covered by third coveringelement 52, in order to form the above-mentioned blood-impervious sealwith second covering element 42. Thus, third covering element 52 may beconfigured to cover a distal sub-portion, and not a proximalsub-portion, of proximal portion 92.

For some applications, such as for the configurations shown in FIGS.1A-B, third support element 50 is configured to extend into secondstent-graft 22 a distance sufficient to help anchor the thirdstent-graft to the second stent-graft, such as at least 4 cm, no morethan 10 cm, and/or between 4 and 10 cm. For some applications, proximalportion 92 has a perimeter that is sufficient to apply aradially-outward force against an inner surface of a wall of secondstent-graft 22, in order to help anchor the third stent-graft to thesecond stent-graft. For example, an axial portion of proximal portion 92having a length of at least 1 cm may have a perimeter that is at least10 greater than of a perimeter of a portion of the second stent-graft inwhich proximal portion 92 is disposed. Typically, third stent-graft 24is deployed such that proximal portion 92 extends into the secondstent-graft in a proximal direction from second lateral opening 44, suchas described hereinbelow with reference to FIGS. 3H-I.

For applications in which fourth stent-graft 26 is provided, the fourthstent-graft is configured to be disposed through third lateral opening54, such that a portion of the fourth stent-graft is disposed withinthird stent-graft 24 (and, optionally, depending on the length of theportion, also within second stent-graft 22, or within both secondstent-graft 22 and first stent-graft 20), and a portion of the fourthstent-graft is disposed outside of the third stent-graft. The third andfourth stent-grafts are configured such that fourth covering element 62forms a blood-impervious seal with third covering element 52 aroundthird lateral opening 54, when the fourth stent-graft is thus disposedthrough the third lateral opening, and third and fourth stent-grafts 24and 26 are in their radially-expanded states. The third and fourthstent-grafts are securely anchored to each other.

For some applications, when fourth stent-graft 26 is disposed throughthird lateral opening 54 and third and fourth stent-grafts 24 and 26 arein their radially-expanded states, a proximal portion 98 of fourthsupport element 60 is disposed within third stent-graft 24, and fourthcovering element 62 does not fully cover proximal portion 98, therebyallowing blood flow through the third stent-graft (i.e., the fourthcovering element does not fully cover proximal sub-portion 70).(Optionally, proximal sub-portion 70 is flared radially outward in aproximal direction at its proximal end.) Typically, at least adistal-most portion of proximal portion 98 is covered by fourth coveringelement 62, in order to form the above-mentioned blood-impervious sealwith third covering element 52. Thus, fourth covering element 62 may beconfigured to cover a distal sub-portion, and not a proximalsub-portion, of proximal portion 98.

For some applications, such as for the configurations shown in FIGS.1A-B, fourth support element 60 is configured to extend into thirdstent-graft 24 a distance sufficient to help anchor the thirdstent-graft to the second stent-graft, such as at least 4 cm, no morethan 10 cm, and/or between 4 and 10 cm. For some applications, proximalportion 98 has a perimeter that is sufficient to apply aradially-outward force against an inner surface of a wall of thirdstent-graft 24, in order to help anchor the fourth stent-graft to thethird stent-graft. For example, an axial portion of proximal portion 98having a length of at least 1 cm may have a perimeter that is at least10% greater than a perimeter of a portion of the third stent-graft inwhich proximal portion 98 is disposed. Typically, fourth stent-graft 26is deployed such that proximal portion 98 extends into the thirdstent-graft in a proximal direction from third lateral opening 54, suchas described hereinbelow with reference to FIGS. 3K-L.

Although FIG. 2 shows the proximal ends of the stent-grafts having theconfiguration shown in FIGS. 1A-B, for some applications, one or more ofthe stent-grafts instead has the flaring proximal end configurationsshown in FIG. 1C.

For some applications, a method is provided that comprises assemblingfirst and second stent-grafts 20 and 22, optionally third stent-graft24, and optionally fourth stent-graft 26, as described hereinabove withreference to FIG. 2, either in situ or ex vivo.

An Exemplary Deployment Procedure for the Configuration in which theFirst Stent-Graft has a Single Lateral Opening

Reference is made to FIGS. 3A-L, which are schematic illustrations of anexemplary transluminal delivery procedure for implanting multi-componentstent-graft system 10, as configured in FIGS. 1A, 1B, 1C, and/or 2, inaccordance with an application of the present invention. FIGS. 3A-Lschematically show a portion of a typical aorta, including a thoracicaorta, which includes an upper part of an ascending aorta 101, an aorticarch 100, and an upper part of a supra-renal descending aorta 102. Alsoshown are the three branches of aortic arch 100: a brachiocephalicartery 103, a left common carotid artery 104, and a left subclavianartery 105. In addition, left and right renal arteries 106 and 107 areshown.

In this exemplary procedure, the stent-grafts of system 10 aretransvascularly (typically percutaneously) introduced into the thoracicaorta via one of the iliac arteries, while the stent-grafts arepositioned in one or more outer tubes of a delivery tool in theirradially-compressed states. Alternatively, for some applications, one ormore of the stent-grafts are deployed via a right subclavian artery,such as described hereinbelow with reference to FIG. 9D.

Deployment of the First Stent-Graft

The exemplary procedure begins with the advancing of a guidewire 120 updescending aorta 102 and into a first one of the branches of aortic arch100, such as left subclavian artery 105, as shown in FIG. 3A.

First stent-graft 20 is initially positioned in its radially-compressedstate within an outer tube 130 of a delivery tool, typically near adistal end 132 of the outer tube (e.g., such that at least one end ofstent-graft 20 is within a distance of distal end 132, which distanceequals the sum of 2 cm and an axial length of the first stent-graft).Outer tube 130 is advanced over guidewire 120, until first stent-graft20 is partially disposed in left subclavian artery 105 and partiallydisposed in the upper part of descending aorta 102, as shown in FIG. 3B.The guidewire is withdrawn, leaving outer tube 130 in place.

As shown in FIG. 3C, the first stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the first stent-graft from theouter tube. Optionally, techniques for holding the first stent-graft inplace may be used that are described hereinbelow with reference to FIGS.10 and 11A-E or FIGS. 12A-C. First stent-graft 20 typicallyself-expands, until it assumes its radially-expanded state, uponreaching its maximum unconstrained size, and/or being constrained fromfurther expansion by the wall of the blood vessels. Alternatively, thefirst stent-graft (and/or the second, third, and/or fourth stent-grafts,as described hereinbelow) is delivered using an over-the-wire (OTW)approach, in which the guidewire is left in place until the stent-graftis expanded, and thereafter the guidewire is withdrawn.

A proximal portion 111 of first stent-graft 20, including proximal end36, is positioned in the upper part of descending aorta 102, and adistal portion 112 of first stent-graft 20 is positioned in leftsubclavian artery 105. First lateral opening 34 is disposed in aorticarch 100 facing upstream, generally toward ascending aorta 101, in avicinity of the bifurcation of aortic arch 100 and left subclavianartery 105. For some applications, proper rotational alignment and/oraxial orientation of the first lateral opening is achieved usingfluoroscopy. For example, first stent-graft 20 may comprise one or moreradiopaque markers in a vicinity of (e.g., on a periphery of) the firstlateral opening.

Deployment of the Second Stent-Graft

A guidewire (either the same guidewire 120 used to deploy the firststent-graft, or a second guidewire) is advanced up descending aorta 102,through a proximal portion of first-stent-graft 20, out of first lateralopening 34, and into a second one of the branches of aortic arch 100,such as left common carotid artery 104, as shown in FIG. 3D.

Second stent-graft 22 is positioned in its radially-compressed statewithin an outer tube of a delivery tool (either the same outer tube 130used to deploy the first stent-graft, or a second outer tube), typicallynear distal end 132 of the outer tube (e.g., such that at least one endof stent-graft 22 is within a distance of distal end 132, which distanceequals the sum of 2 cm and an axial length of the first stent-graft).Outer tube 130 is advanced over guidewire 120, until second stent-graft22 is partially disposed in left common carotid artery 104 and partiallydisposed within radially-expanded first stent-graft 20 in the upper partof descending aorta 102, as shown in FIG. 3E. The guidewire iswithdrawn, leaving outer tube 130 in place.

As shown in FIG. 3F, the second stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the second stent-graft fromthe outer tube. Optionally, techniques for holding the secondstent-graft in place may be used that are described hereinbelow withreference to FIGS. 10 and 11A-E or FIGS. 12A-C. Second stent-graft 22typically self-expands, until it assumes its radially-expanded state,upon reaching its maximum unconstrained size, and/or being constrainedfrom further expansion by the wall of the blood vessels.

A proximal portion of second stent-graft 22, including proximal end 46,is positioned within first stent-graft 20 in the upper part ofdescending aorta 102, and a distal portion of second stent-graft 22,including distal end 48, is positioned in left common carotid artery104. For application in which third stent-graft 24 is provided, andsecond stent-graft 22 is shaped so as to define second lateral opening44, the second lateral opening is disposed in aortic arch 100 facingupstream, generally toward ascending aorta 101, in a vicinity of thebifurcation of aortic arch 100 and left common carotid artery 104. Forsome applications, proper rotational alignment and/or axial orientationof the second lateral opening is achieved using fluoroscopy. Forexample, second stent-graft 22 may comprise one or more radiopaquemarkers in a vicinity (e.g., on a periphery of) the second lateralopening.

Second stent-graft 22 is thus adapted for transluminal delivery in itsradially-compressed state through a portion of first stent-graft 20 andfirst lateral opening 34, while the first stent-graft is in itsradially-expanded state.

Deployment of the Third Stent-Graft

For applications in which third stent-graft 24 is provided, a guidewire(either the same guidewire 120 used to deploy the first and/or secondstent-grafts, or an additional guidewire) is advanced up descendingaorta 102 and into a third one of the branches of aortic arch 100, suchas brachiocephalic artery 103, as shown in FIG. 3G.

Third stent-graft 24 is positioned in its radially-compressed statewithin an outer tube of a delivery tool (either the same outer tube 130used to deploy the first and/or second stent-grafts, or another outertube), typically near distal end 132 of the outer tube (e.g., such thatat least one end of stent-graft 24 is within a distance of distal end132, which distance equals the sum of 2 cm and an axial length of thefirst stent-graft). Outer tube 130 is advanced over guidewire 120, untilthird stent-graft 24 is partially disposed in brachiocephalic artery 103and partially disposed within radially-expanded second stent-graft 22 inaortic arch 100, as shown in FIG. 3H. The guidewire is withdrawn,leaving outer tube 130 in place.

As shown in FIG. 3I, the third stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the third stent-graft from theouter tube. Optionally, techniques for holding the third stent-graft inplace may be used that are described hereinbelow with reference to FIGS.10 and 11A-E or FIGS. 12A-C. Third stent-graft 24 typicallyself-expands, until it assumes its radially-expanded state, uponreaching its maximum unconstrained size, and/or being constrained fromfurther expansion by the wall of the blood vessels.

A proximal portion of third stent-graft 24 is positioned within secondstent-graft 22 in aortic arch 100, and a distal portion of thirdstent-graft 24, including distal end 58, is positioned inbrachiocephalic artery 103. For application in which fourth stent-graft26 is provided, and third stent-graft 24 is shaped so as to define thirdlateral opening 54, the third lateral opening is disposed in aortic arch100 facing upstream, generally toward ascending aorta 101, in a vicinityof the bifurcation of aortic arch 100 and brachiocephalic artery 103.For some applications, proper rotational alignment and/or axialorientation of the third lateral opening is achieved using fluoroscopy.For example, third stent-graft 24 may comprise one or more radiopaquemarkers in a vicinity (e.g., on a periphery of) the third lateralopening.

Third stent-graft 24 is thus adapted for transluminal delivery in itsradially-compressed state through, sequentially, (a) a portion of firststent-graft 20, (b) first lateral opening 34, (c) a portion of secondstent-graft 22, and (d) second lateral opening 44, while the first andsecond stent-grafts are in their radially-expanded states.

Deployment of the Fourth Stent-Graft

For applications in which fourth stent-graft 26 is provide, a guidewire(either the same guidewire 120 used to deploy the first, second, and/orthird stent-grafts, or an additional guidewire) is advanced updescending aorta 102 and into the upper part of ascending aorta 101, asshown in FIG. 3J.

Fourth stent-graft 26 is positioned in its radially-compressed statewithin an outer tube of a delivery tool (either the same outer tube 130used to deploy the first, second, and/or third stent-grafts, or anadditional outer tube), typically near distal end 132 of the outer tube(e.g., such that at least one end of stent-graft 26 is within a distanceof distal end 132, which distance equals the sum of 2 cm and an axiallength of the first stent-graft). Outer tube 130 is advanced overguidewire 120, until fourth stent-graft 26 is partially disposed in theupper part of ascending aorta 101 and partially disposed withinradially-expanded third stent-graft 24 in aortic arch 100, as shown inFIG. 3K. The guidewire is withdrawn, leaving outer tube 130 in place.

As shown in FIG. 3L, the fourth stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the fourth stent-graft fromthe outer tube. Optionally, techniques for holding the fourthstent-graft in place may be used that are described hereinbelow withreference to FIGS. 10 and 11A-E or FIGS. 12A-C. Fourth stent-graft 26typically self-expands, until it assumes its radially-expanded state,upon reaching its maximum unconstrained size, and/or being constrainedfrom further expansion by the wall of the blood vessels.

A proximal portion of fourth stent-graft 26 is positioned within thirdstent-graft 24 (and, optionally, in second stent-graft 22) in aorticarch 100, and a distal portion of fourth stent-graft 26, includingdistal end 68, is positioned in aortic arch 100 and/or the upper part ofascending aorta 101.

Fourth stent-graft 26 is thus adapted for transluminal delivery when inits radially-compressed state through, sequentially, (a) a portion offirst stent-graft 20, (b) first lateral opening 34, (c) a portion ofsecond stent-graft 22, (d) second lateral opening 44, (e) a portion ofthird stent-graft 24, and (f) third lateral opening 54 while first,second, and third stent-grafts 20, 22, and 24 are in theirradially-expanded states.

As can be seen in FIG. 3L, upon deployment of all four stent-grafts,multi-component stent-graft system 10 defines a blood-flow path fromascending aorta 101, over aortic arch 100, and to descending aorta 102.Multi-component stent-graft system 10 additionally provides blood-flowpaths to the three branches of the aortic arch: brachiocephalic artery103, left common carotid artery 104, and left subclavian artery 105.

First Stent-Graft Having Three Lateral Openings

Reference is now made to FIG. 4, which is a schematic illustration ofanother configuration of multi-component stent-graft system 10, inaccordance with an application of the present invention. In thisconfiguration, multi-component stent-graft system 10 comprises (a) firststent-graft 20, (b) second stent-graft 22, (c) third stent-graft 24, and(d) fourth stent-graft 26, typically configured as describedhereinbelow. Except as described below, the stent-grafts are generallysimilar to the configurations of the stent-grafts described hereinabovewith reference to FIGS. 1A-C and 2. The stent-grafts are configured toassume radially-compressed states, such as when initially positioned inone or more outer tubes of one or more delivery tools, as describedhereinbelow with reference to FIGS. 6A, 6B, 6E, and 6G, and to assumeradially-expanded states upon being deployed from the outer tube(s), asdescribed hereinbelow with reference to FIGS. 6B-D and 6F-H. FIG. 4shows the stent-grafts in their radially-expanded states. For someapplications, the stent-grafts are relaxed in their radially-expandedstates. For some applications, the stent-grafts are configured to beself-expanding. For example, they may be heat-set to assume theirradially-expanded states.

The First Stent-Graft

In the configuration shown in FIG. 4, first covering element 32 andfirst support element 30 are shaped so as to together define three(e.g., exactly three) first lateral openings 34 through firststent-graft 20 when the first stent-graft is in its radially-expandedstate:

-   -   a proximal superior first lateral opening 34A;    -   a distal superior first lateral opening 34B; and    -   a distal inferior first lateral opening 34C.        Typically, when first stent-graft 20 is unconstrained in its        radially-expanded state, proximal and distal superior first        lateral openings 34A and 34B face in a first radial direction,        and distal inferior first lateral opening 34C faces in a second        radially direction generally circumferentially opposite the        first radial direction. For example, if the stent-graft is        viewed from one end, proximal and distal superior first lateral        openings 34A and 34B may be disposed at between 11 o'clock and 1        o'clock (e.g., at 12 o'clock), and distal inferior first lateral        opening 34C may disposed at between 5 o'clock and 7 o'clock        (e.g., at 6 o'clock).

Typically, distal inferior first lateral opening 34C is not axiallyaligned with either of proximal superior first lateral opening 34A ordistal superior first lateral opening 34B. Typically, distal inferiorfirst lateral opening 34C does not axially overlap with either ofproximal superior first lateral opening 34A or distal superior firstlateral opening 34B.

For some applications, stent-graft 20 narrows in a vicinity of proximalsuperior first lateral opening 34A and/or distal superior first lateralopening 34B, with respect to a portion of stent-graft 20 proximal to theproximal superior first lateral opening 34A (i.e., the perimeter is lessat one or both of the lateral openings than in the more proximalportion). Such narrowing may increase the maneuverability of thirdand/or fourth stent-grafts 24 and 26 when advancing these stent-graftsinto left common carotid artery 104 and left subclavian artery 105, byproviding more space between the superior lateral openings and thebifurcations of these arteries.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, first perimeter P1 of first end 36 of the firststent-graft is greater than second perimeter P2 of second end 38 of thefirst stent-graft, and/or a first cross-sectional area of the first end36 is greater than a second cross-sectional area of second end 38. Forexample, first perimeter P1 may equal at least 150% of second perimeterP2, such as at least 250%, or at least 400%, and/or the firstcross-sectional area may equal at least 225% of the secondcross-sectional area, such as at least 625%, or at least 1600%.

For example, first perimeter P1 may be at least 7.5 cm, no more than 15cm, and/or between 7.5 and 15 cm, such as at least 9 cm, no more than 13cm, and/or between 9 and 13 cm, and second perimeter P2 may be at least2.5 cm, no more than 5.7 cm, and/or between 2.5 and 5.7 cm, such as atleast 3 cm, no more than 4.5 cm, and/or between 3 and 4.5 cm.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, a perimeter of each of proximal superior firstlateral opening 34A and distal superior first lateral opening 34B is atleast 2.5 cm, no more than 5 cm, and/or between 2.5 and 5 cm, and aperimeter of distal inferior first lateral opening 34C is at least 4.5cm, no more than 12 cm, and/or between 4.5 and 12 cm.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, a perimeter of distal inferior first lateralopening 34C is at least 25%, e.g., at least 40%, or at least 60% offirst perimeter P1, and/or at least 50%, e.g., at least 75%, or at least100% of second perimeter P2. For some applications, first perimeter P1does not equal second perimeter P2, and the perimeter of distal inferiorfirst lateral opening 34C is at least 60% of the lesser of first andsecond perimeters P1 and P2.

For some applications, first stent-graft 20, when unconstrained in itsradially-expanded state, has an axial length of at least 15 cm, no morethan 40 cm, and/or between 15 and 40 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved.) For some applications,first stent-graft 20, when unconstrained in its radially-expanded state,has a greatest perimeter (at any axial location along the stent-graft)of at least 12 cm, no more than 21 cm, and/or between 12 and 21 cm.

For some applications, a closest axial distance D1 between proximalsuperior first lateral opening 34A and distal superior first lateralopening 34B is between 0.5 and 2 cm. For some applications, a distanceD2 between the centers of distal superior first lateral opening 34B anddistal inferior first lateral opening 34C is between 0 and 5 cm.

For some applications, such dimensions allow the first stent-graft to bepositioned such that (a) a proximal, radially larger, portion of thestent-graft, including the proximal end thereof, is disposed in theaorta downstream from the bifurcation with the left subclavian artery,at least partially in the upper part of the descending aorta, (b) adistal, radially smaller, portion of the stent-graft, including thedistal end thereof, is disposed in the brachiocephalic artery, and (c) amiddle portion of the stent-graft is positioned in the aortic arch, suchas described hereinbelow with reference to FIG. 6B. For someapplications, the proximal portion of the stent-graft has an averageperimeter that is greater than (e.g., between 5% and 15% greater than)an average perimeter of the portion of the aorta in which it is disposed(excluding expansion of the aorta due to the aneurysm, i.e., assumingthe aorta were healthy). For some applications, the distal portion ofthe stent-graft has an average perimeter that is greater than (e.g.,between 5% and 15% greater than) the average perimeter of the portion ofthe brachiocephalic artery in which it is disposed. For someapplications, the middle portion of the stent-graft has an averageperimeter that is less than (e.g., between 50% and 70% less than) anaverage perimeter of the portion of the aortic arch in which it isdisposed (excluding expansion of the aortic arch due to the aneurysm,i.e., assuming the aortic arch were healthy).

The Second Stent-Graft

In the configuration shown in FIG. 4, second covering element 42 andsecond support element 40 of second stent-graft 22 are shaped so as totogether define no lateral openings.

Typically, proximal end 46 of second stent-graft 22 is outwardly flaredin a proximal direction when the stent-graft is unconstrained in itsradially-expanded state. Optionally, the stent-graft is additionallyslightly indented radially inward immediately distal to the outwardflare. Typically, covering element 42 covers at least a distal portionof the outward flare. The flare enables secure anchoring of the secondstent-graft to the first stent-graft, such as described hereinbelow withreference to FIGS. 5 and 6D.

For some applications, when second stent-graft 22 is unconstrained inits radially-expanded state, fourth perimeter P4 of second (distal) end48 of the second stent-graft is substantially greater than thirdperimeter P3 of first (proximal) end 46 of the second stent-graft, suchas at least 150% of P3, e.g., at least 200%. For some applications,third perimeter P3 is at least 3 cm, no more than 7 cm, and/or between 3and 7 cm. For some applications, fourth perimeter P4 is at least 6 cm,no more than 19 cm, and/or between 6 and 19 cm.

For some applications, second stent-graft 22, when unconstrained in itsradially-expanded state, has an axial length of at least 4 cm, no morethan 20 cm, and/or between 4 and 20 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved.) For some applications,second stent-graft 22, when unconstrained in its radially-expandedstate, has a greatest perimeter (at any axial location along thestent-graft) of at least 6 cm, no more than 10 cm, and/or between 6 and10 cm.

For some applications, such dimensions allow the second stent-graft tobe positioned such that (a) a proximal, radially smaller, portion of thestent-graft, including the proximal end thereof, is disposed in theaortic arch in the first stent-graft, and (b) a distal, radially larger,portion of the stent-graft, including the distal end thereof, isdisposed in the aortic arch and/or upper part of descending aorta, suchas described hereinbelow with reference to FIG. 6D. For someapplications, the proximal portion of the stent-graft has an averageperimeter that is less than (e.g., between 30% and 70% less than) anaverage perimeter of the portion of the aortic arch in which it isdisposed (excluding expansion of the aortic arch due to the aneurysm,i.e., assuming the aortic arch were healthy) and at least 10% greaterthan the perimeter of distal inferior first lateral opening 34C of thefirst stent-graft. For some applications, the distal portion of thestent-graft has an average perimeter that is greater than (e.g., between5% and 15% greater than) the average perimeter of the portion of theaorta in which it is disposed (excluding expansion of the aorta due tothe aneurysm, i.e., assuming the aorta were healthy).

The Third and Fourth Stent-Grafts

For some applications of the configuration shown in FIG. 4, third andfourth stent-grafts 24 and 26 are identical or generally similar inshape and dimensions. In the configuration shown in FIG. 4, thirdcovering element 52 and third support element 50 of third stent-graft 24are shaped so as to together define no lateral openings, and fourthcovering element 62 and fourth support element 60 of fourth stent-graft26 are shaped so as to together define no lateral openings.

Typically, proximal ends 56 and 66 of third and fourth stent-grafts 24and 26 are outwardly flared in a proximal direction when thestent-grafts are unconstrained in their radially-expanded state.Optionally, the stent-grafts are additionally slightly indented radiallyinward immediately distal to the outward flares. Typically, coveringelements 52 and 62 cover at least a distal portion of the outwardflares. The flares enable secure anchoring of the third and fourthstent-grafts to the first stent-graft, such as described hereinbelowwith reference to FIGS. 6F and 6H.

For some applications, when third stent-graft 24 is unconstrained in itsradially-expanded state, fifth perimeter P5 of first (proximal) end 56of the third stent-graft is approximately equal to, or slightly greaterthan, sixth perimeter P6 of second (distal) end 58 of the thirdstent-graft, such as within 90% to 130% of P6. Similarly, for someapplications, when fourth stent-graft 26 is unconstrained in itsradially-expanded state, seventh perimeter P7 of first (proximal) end 66of the fourth stent-graft is approximately equal to, or slightly greaterthan, eighth perimeter P8 of second (distal) end 68 of the fourthstent-graft, such as within 90% to 130% of P8. For some applications,each of fifth perimeter P5, sixth perimeter P6, seventh perimeter P7,and eighth perimeter P8 is at least 2.5 cm, no more than 6.3 cm, and/orbetween 2.5 and 6.3 cm.

For some applications, each of third and fourth stent-grafts 24 and 26,when unconstrained in their radially-expanded states, has an axiallength of at least 3 cm, no more than 10 cm, and/or between 3 and 10 cm.(The axial length is measured along a central longitudinal axis of thestent-grafts, including in applications in which the stent-grafts arecurved.) For some applications, each of third and fourth stent-grafts 24and 26, when unconstrained in their radially-expanded states, has agreatest perimeter (at any axial location along the stent-grafts) of atleast 2.5 cm, no more than 6.3 cm, and/or between 2.5 and 6.3 cm.

For some applications, such dimensions allow the third stent-graft to bepositioned such that (a) a proximal portion of the stent-graft isdisposed in the aorta in the first stent-graft, and (b) a distal portionof the stent-graft, including the distal end thereof, is disposed in theleft common carotid artery, such as described hereinbelow with referenceto FIG. 6F. For some applications, the proximal portion of thestent-graft has an average perimeter that is less than (e.g., between30% and 70% less than) an average perimeter of the portion of the aorticarch in which it is disposed (excluding expansion of the aortic arch dueto the aneurysm, i.e., assuming the aortic arch were healthy). For someapplications, the distal portion of the stent-graft has an averageperimeter that is greater than (e.g., between 5% and 15% greater than)the average perimeter of the portion of the left common carotid arteryin which it is disposed.

For some applications, such dimensions allow the fourth stent-graft tobe positioned such that (a) a proximal portion of the stent-graft isdisposed in the aorta in the first stent-graft, and (b) a distal portionof the stent-graft, including the distal end thereof, is disposed in theleft subclavian artery, such as described hereinbelow with reference toFIG. 6H. For some applications, the proximal portion of the stent-grafthas an average perimeter that is less than (e.g., between 30% and 70%less than) an average perimeter of the portion of the aortic arch inwhich it is disposed (excluding expansion of the aortic arch due to theaneurysm, i.e., assuming the aortic arch were healthy). For someapplications, the distal portion of the stent-graft has an averageperimeter that is greater than (e.g., between 5% and 10% greater than)the average perimeter of the portion of the left subclavian artery inwhich it is disposed.

Additional Configuration Detail

For some applications, stent-grafts 20, 22, 24, and 26 are configured(e.g., heat-set) to have generally straight longitudinal axes whenunconstrained in their radially-expanded states, i.e., no forces areapplied to the stent-grafts by a delivery tool, walls of a blood vessel,or otherwise. The stent-grafts typically assumed curved shapes whenplaced in respective blood vessels because of the force applied to thestent-grafts by the walls of the blood vessels, such as shown in FIGS.6A-H.

For other applications, stent-grafts 20, 22, 24, and 26 are configured(e.g., heat-set) to have generally curved longitudinal axes whenunconstrained in their radially-expanded states, i.e., no forces areapplied to the stent-grafts by a delivery tool, walls of a blood vessel,or otherwise. This curvature may help properly position the stent-graftswith respect to one another, such as shown in FIGS. 5 and 6A-H. Thisconfiguration is similar to the curved configuration shown in FIG. 1B.For some applications, at least one the stent-grafts is generallystraight, while at least another one of the stent-grafts is generallycurved.

Typically, first and second stent-grafts 20 and 22 are not fixed to oneother when they are in their radially-compressed states. Likewise,first, second, and third stent-grafts 20, 22, and 24 are typically notfixed to one other when they are in their radially-compressed states.Furthermore, first, second, third, and fourth stent-grafts 20, 22, 24,and 26 are typically not fixed to one other when they are in theirradially-compressed states. In other words, the stent-grafts areinitially provided as separate, non-connected components, as shown inFIG. 4 (although they are typically initially positioned in outertube(s) of delivery tool(s), as described hereinbelow), which aretypically assembled in situ. Typically, first and second coveringelement 32 and 42 are not fixed to one other when they are in theirradially-compressed states. Likewise, first, second, and third coveringelement 32, 42, and 52 are typically not fixed to one other when first,second, and third stent-grafts 20, 22, and 24 are in theirradially-compressed states. Furthermore, first, second, third, andfourth covering elements 32, 42, 52, and 62 are typically not fixed toone other when first, second, third, and fourth stent-grafts 20, 22, 24,and 26 are in their radially-compressed states.

For some applications, one or more (e.g., all) of the lateral openingsare circumscribed by respective generally annular structural stentelements of the support elements.

Assembly of the Stent-Grafts

FIG. 5 is a schematic illustration of multi-component stent-graft system10, having the configuration described with reference to FIG. 4, in anassembled state, in accordance with an application of the presentinvention. As mentioned above, such assembly is typically performed insitu during an implantation procedure, but such assembly may also beperformed ex vivo. First, second, third, and fourth stent-grafts 20, 22,24, and 26 are shown in FIG. 5 in their radially-expanded states. Secondstent-graft 22 is configured to be disposed through distal inferiorfirst lateral opening 34C, such that a portion (e.g., the flaredportion) of the second stent-graft is disposed within first stent-graft20, and a portion of the second stent-graft is disposed outside of thefirst stent-graft. The first and second stent-grafts are configured suchthat second covering element 42 forms a blood-impervious seal with firstcovering element 32 around distal inferior first lateral opening 34C,when the second stent-graft is thus disposed through the distal inferiorfirst lateral opening, and first and second stent-grafts 20 and 22 arein their radially-expanded states. The first and second stent-grafts aresecurely anchored to each other. The blood-impervious seal is typicallyformed because support element 30 of the first stent-graft is configuredto having a resting perimeter that is greater than the perimeter of thedistal inferior first lateral opening, such that the distal inferiorfirst lateral opening squeezes the second stent-graft when the secondstent-graft expands.

Third stent-graft 24 is configured to be disposed through distalsuperior first lateral opening 34B, such that a portion (e.g., theflared portion) of the third stent-graft is disposed within firststent-graft 20, and a portion of the third stent-graft is disposedoutside of the first stent-graft. The first and third stent-grafts areconfigured such that third covering element 52 forms a blood-imperviousseal with first covering element 32 around distal superior first lateralopening 34B, when the third stent-graft is thus disposed through thedistal superior first lateral opening, and first and third stent-grafts20 and 24 are in their radially-expanded states. The first and thirdstent-grafts are securely anchored to each other.

Fourth stent-graft 26 is configured to be disposed through proximalsuperior first lateral opening 34A, such that a portion (e.g., theflared portion) of the fourth stent-graft is disposed within firststent-graft 20, and a portion of the fourth stent-graft is disposedoutside of the first stent-graft. The first and fourth stent-grafts areconfigured such that fourth covering element 62 forms a blood-imperviousseal with first covering element 32 around proximal superior firstlateral opening 34A, when the fourth stent-graft is thus disposedthrough the proximal superior first lateral opening, and first andfourth stent-grafts 20 and 26 are in their radially-expanded states. Thefirst and fourth stent-grafts are securely anchored to each other.

For some applications, a method is provided that comprises assemblingfirst, second, third, and fourth stent-grafts 20, 22, 24, and 26, asdescribed hereinabove with reference to FIG. 5, either in situ or exvivo.

An Exemplary Deployment Procedure for the Configuration in which theFirst Stent-Graft has Three Lateral Openings

Reference is made to FIGS. 6A-H, which are schematic illustrations of anexemplary transluminal delivery procedure for implanting multi-componentstent-graft system 10, as configured in FIGS. 4 and 5, in accordancewith an application of the present invention. In this exemplaryprocedure, the stent-grafts of system 10 are transvascularly (typicallypercutaneously) introduced into aortic arch 100 via one of the iliacarteries, while the stent-grafts are positioned in one or more outertubes of a delivery tool in their radially-compressed states.Alternatively, for some applications, one or more of the stent-graftsare deployed via a right subclavian artery, such as describedhereinbelow with reference to FIG. 9D.

Deployment of the First Stent-Graft

First stent-graft 20 is initially positioned in its radially-compressedstate within outer tube 130 of a delivery tool, typically near distalend 132 of the outer tube (e.g., such that at least one end ofstent-graft 20 is within a distance of distal end 132, which distanceequals the sum of 2 cm and an axial length of the first stent-graft).The exemplary procedure begins with the advancing of guidewire 120 updescending aorta 102 and into a first one of the branches of the aorticarch, such as brachiocephalic artery 103. Outer tube 130 is advancedover guidewire 120, until first stent-graft 20 is partially disposed inbrachiocephalic artery 103, partially disposed in aortic arch 100, andpartially disposed an upper part of descending aorta 102, as shown inFIG. 6A. The guidewire is withdrawn, leaving outer tube 130 in place.

As shown in FIG. 6B, the first stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the first stent-graft from theouter tube. Optionally, techniques for holding the first stent-graft inplace may be used that are described hereinbelow with reference to FIGS.10 and 11A-E or FIGS. 12A-C. First stent-graft 20 typicallyself-expands, until it assumes its radially-expanded state, uponreaching its maximum unconstrained size, and/or being constrained fromfurther expansion by the wall of the blood vessels. Alternatively, thefirst stent-graft (and/or the second, third, and/or fourth stent-grafts,as described hereinbelow) is delivered using an over-the-wire (OTW)approach, in which the guidewire is left in place until the stent-graftis expanded, and thereafter the guidewire is withdrawn.

A proximal portion 140 of first stent-graft 20, including proximal end36, is positioned in the upper part of descending aorta 102, a middleportion 142 of first stent-graft 20 is positioned in aortic arch 100,and a distal portion 144 of first stent-graft 20, including distal end38, is positioned in brachiocephalic artery 103. Proximal superior firstlateral opening 34A faces toward and is aligned with left subclavianartery 105, and distal superior first lateral opening 34B faces towardand is aligned with left common carotid artery 104. Distal inferiorfirst lateral opening 34C is disposed in aortic arch 100 facingupstream, generally toward ascending aorta 101, in a vicinity of thebifurcation of aortic arch 100 and brachiocephalic artery 103. For someapplications, proper rotational alignment and/or axial orientation ofthe first lateral openings is achieved using fluoroscopy. For example,first stent-graft 20 may comprise one or more radiopaque markers in avicinity (e.g., on a periphery of) the first lateral openings.

Deployment of the Second Stent-Graft

Also as shown in FIG. 6B, second stent-graft 22 is positioned in itsradially-compressed state within an outer tube of a delivery tool(either the same outer tube 130 used to deploy the first stent-graft, ora second outer tube), typically near distal end 132 of the outer tube(e.g., such that at least one end of stent-graft 22 is within a distanceof distal end 132, which distance equals the sum of 2 cm and an axiallength of the first stent-graft). A guidewire (either the same guidewire120 used to deploy the first stent-graft, or a second guidewire) isadvanced up descending aorta 102, through a proximal portion of firststent-graft 20, out of distal inferior first lateral opening 34C, andinto aortic arch 100 and/or the upper part of ascending aorta 101. Outertube 130 is advanced over guidewire 120, until second stent-graft 22 ispartially disposed in the upper part of ascending aorta 101 andpartially disposed within radially-expanded first stent-graft 20 inaortic arch 100. The guidewire is withdrawn, leaving outer tube 130 inplace.

As shown in FIGS. 6C and 6D, the second stent-graft is held in place asouter tube 130 is withdrawn, thereby delivering the second stent-graftfrom the outer tube. Optionally, techniques for holding the secondstent-graft in place may be used that are described hereinbelow withreference to FIGS. 10 and 11A-E or FIGS. 12A-C. Second stent-graft 22typically self-expands, until it assumes its radially-expanded state,upon reaching its maximum unconstrained size, and/or being constrainedfrom further expansion by the wall of the blood vessels. FIG. 6C showsthe second stent-graft partially released from outer tube 130 (and thuspartially expanded), and FIG. 6D shows the second stent-graft fullyreleased from the outer tube (and thus fully expanded).

A proximal portion of second stent-graft 22, including proximal end 46,is positioned within first stent-graft 20 in aortic arch 100, and adistal portion of second stent-graft 22, including distal end 48, ispositioned in the upper part of ascending aorta 101.

Second stent-graft 22 is thus adapted for transluminal delivery in itsradially-compressed state through a portion of first stent-graft 20 andone of first lateral openings 34 (e.g., distal inferior first lateralopening 34C), while the first stent-graft is in its radially-expandedstate.

Deployment of the Third Stent-Graft

Third stent-graft 24 is positioned in its radially-compressed statewithin an outer tube of a delivery tool (either the same outer tube 130used to deploy the first and/or second stent-grafts, or another outertube), typically near distal end 132 of the outer tube (e.g., such thatat least one end of stent-graft 24 is within a distance of distal end132, which distance equals the sum of 2 cm and an axial length of thefirst stent-graft). A guidewire (either the same guidewire 120 used todeploy the first and/or second stent-grafts, or an additional guidewire)is advanced up descending aorta 102, through a proximal portion of firststent-graft 20, out of one of proximal superior first lateral opening34A and distal superior first lateral opening 34B, and into a second oneof the branches of aortic arch 100, such as left common carotid artery104 or left subclavian artery 105. In the application shown in FIG. 6E,the guidewire is advanced out of distal superior first lateral opening34B and into left common carotid artery 104. Alternatively, theguidewire is instead advanced out of proximal superior first lateralopening 34A and into left subclavian artery 105, in which case thefourth stent-graft, described below, is instead advanced out of distalsuperior first lateral opening 34B and into left common carotid artery104. Outer tube 130 is advanced over guidewire 120, until thirdstent-graft 24 is partially disposed in the selected one of left commoncarotid artery 104 and left subclavian artery 105 (left common carotidartery 104 in FIG. 6E) and partially disposed within radially-expandedsecond stent-graft 22 in the aortic arch, as shown in FIG. 6E. Theguidewire is withdrawn, leaving outer tube 130 in place.

As shown in FIG. 6F, the third stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the third stent-graft from theouter tube. Optionally, techniques for holding the third stent-graft inplace may be used that are described hereinbelow with reference to FIGS.10 and 11A-E or FIGS. 12A-C. Third stent-graft 24 typicallyself-expands, until it assumes its radially-expanded state, uponreaching its maximum unconstrained size, and/or being constrained fromfurther expansion by the wall of the blood vessels.

A proximal portion of third stent-graft 24, including proximal end 56,is positioned within first stent-graft 20 in aortic arch 100, and adistal portion of third stent-graft 24, including distal end 58, ispositioned in left common carotid artery 104.

Third stent-graft 24 is thus adapted for transluminal delivery in itsradially-compressed state through a portion of first stent-graft 20 andone of first lateral openings 34, such as one of proximal superior firstlateral opening 34A and distal superior first lateral opening 34B, whilethe first stent-graft is in its radially-expanded state.

Deployment of the Fourth Stent-Graft

Fourth stent-graft 26 is positioned in its radially-compressed statewithin an outer tube of a delivery tool (either the same outer tube 130used to deploy the first, second, and/or third stent-grafts, or anadditional outer tube), typically near distal end 132 of the outer tube(e.g., such that at least one end of stent-graft 26 is within a distanceof distal end 132, which distance equals the sum of 2 cm and an axiallength of the first stent-graft). A guidewire (either the same guidewire120 used to deploy the first, second, and/or third stent-grafts, or anadditional guidewire) is advanced up descending aorta 102, through aproximal portion of first stent-graft 20, out of one of proximalsuperior first lateral opening 34A and distal superior first lateralopening 34B, and into a second one of the branches of aortic arch 100,such as left common carotid artery 104 or left subclavian artery 105. Inthe application shown in FIG. 6G, the guidewire is advanced out ofproximal superior first lateral opening 34A and into left subclavianartery 105. Alternatively, the guidewire stent-graft is instead advancedout of distal superior first lateral opening 34B and into left commoncarotid artery 104, in which case the third stent-graft, describedabove, is instead advanced out of proximal superior first lateralopening 34A and into left subclavian artery 105. Outer tube 130 isadvanced over guidewire 120, until fourth stent-graft 26 is partiallydisposed in the selected one of left common carotid artery 104 and leftsubclavian artery 105 (left subclavian artery 105 in FIG. 6G) andpartially disposed within radially-expanded second stent-graft 22 in theaortic arch, as shown in FIG. 6G. The guidewire is withdrawn, leavingouter tube 130 in place.

As shown in FIG. 6H, the fourth stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the fourth stent-graft fromthe outer tube. Optionally, techniques for holding the fourthstent-graft in place may be used that are described hereinbelow withreference to FIGS. 10 and 11A-E or FIGS. 12A-C. Fourth stent-graft 26typically self-expands, until it assumes its radially-expanded state,upon reaching its maximum unconstrained size, and/or being constrainedfrom further expansion by the wall of the blood vessels.

A proximal portion of fourth stent-graft 26, including proximal end 66,is positioned within first stent-graft 20 in aortic arch 100, and adistal portion of fourth stent-graft 26, including distal end 68, ispositioned in left subclavian artery 105.

Fourth stent-graft 26 is thus adapted for transluminal delivery in itsradially-compressed state through a portion of first stent-graft 20 andone of first lateral openings 34, such as one of proximal superior firstlateral opening 34A and distal superior first lateral opening 34B, whilethe first stent-graft is in its radially-expanded state.

As can be seen in FIG. 6H, upon deployment of all four stent-grafts,multi-component stent-graft system 10 defines a blood-flow path fromascending aorta 101, over aortic arch 100, and to descending aorta 102.Multi-component stent-graft system 10 additionally provides blood-flowpaths to the three branches of the aortic arch: brachiocephalic artery103, left common carotid artery 104, and left subclavian artery 105.

First Stent-Graft Having Two Lateral Openings

Reference is now made to FIG. 7, which is a schematic illustration ofanother configuration of multi-component stent-graft system 10, inaccordance with an application of the present invention. In thisconfiguration, multi-component stent-graft system 10 comprises (a) firststent-graft 20, (b) second stent-graft 22, (c) third stent-graft 24, and(d) fourth stent-graft 26, typically configured as describedhereinbelow. Except as described below, the stent-grafts are generallysimilar to the configurations of the stent-grafts described hereinabovewith reference to FIGS. 1A-C and 2. The stent-grafts are configured toassume radially-compressed states, such as when initially positioned inone or more outer tubes of one or more delivery tools, as describedhereinbelow with reference to FIGS. 9A, 9C, 9D, and 9F, and to assumeradially-expanded states upon being deployed from the outer tube(s), asdescribed hereinbelow with reference to FIGS. 9C, 9D, 9E, and 9G. FIG. 7shows the stent-grafts in their radially-expanded states. For someapplications, the stent-grafts are relaxed in their radially-expandedstates. For some applications, the stent-grafts are configured to beself-expanding. For example, they may be heat-set to assume theirradially-expanded states.

The First Stent-Graft

In the configuration shown in FIG. 7, first covering element 32 andfirst support element 30 are shaped so as to together define two firstlateral openings 34 through first stent-graft 20 when the firststent-graft is in its radially-expanded state:

-   -   a superior first lateral opening 34D; and    -   an inferior first lateral opening 34E.        Typically, when first stent-graft 20 is unconstrained in its        radially-expanded state, superior first lateral opening 34D is        disposed on a first side of first stent-graft 20, and inferior        first lateral opening 34E is disposed on a second side of the        first stent-graft generally circumferentially opposite the first        side. For example, if the stent-graft is viewed from one end,        superior first lateral opening 34D may be disposed at between 11        o'clock and 1 o'clock (e.g., at 12 o'clock), and inferior first        lateral opening 34E may disposed at between 5 o'clock and 7        o'clock (e.g., at 6 o'clock).

For some applications, stent-graft 20 narrows in a vicinity of superiorfirst lateral opening 34D, with respect to a portion of stent-graft 20proximal to the superior first lateral opening 34D (i.e., the perimeteris less at the lateral opening than in the more proximal portion). Suchnarrowing may increase the maneuverability of second stent-graft 22 whenadvancing the second stent-graft into left subclavian artery 105, byproviding more space between the superior lateral opening and thebifurcation of the artery.

Typically, inferior first lateral opening 34E is not axially alignedwith superior first lateral opening 34D. Typically, inferior firstlateral opening 34E does not axially overlap with superior first lateralopening 34D.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, first perimeter P1 of first end 36 of the firststent-graft is greater than second perimeter P2 of second end 38 of thefirst stent-graft, and/or a first cross-sectional area of the first end36 is greater than a second cross-sectional area of second end 38. Forexample, first perimeter P1 may equal at least 150% of second perimeterP2, such as at least 250%, or at least 400%, and/or the firstcross-sectional area may equal at least 225% of the secondcross-sectional area, such as at least 625%, or at least 1600%.

For example, first perimeter P1 may be at least 7.5 cm, no more than 15cm, and/or between 7.5 and 15 cm, and second perimeter P2 may be atleast 2.5 cm, no more than 5.7 cm, and/or between 2.5 and 5.7 cm.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, a perimeter of superior first lateral opening34D is at least 2.5 cm, no more than 5 cm, and/or between 2.5 and 5 cm,and a perimeter of inferior first lateral opening 34E is at least 4.5cm, no more than 12 cm, and/or between 4.5 and 12 cm.

For some applications, when first stent-graft 20 is unconstrained in itsradially-expanded state, a perimeter of inferior first lateral opening34E is at least 25%, e.g., at least 40%, or at least 60% of firstperimeter P1, and/or at least 50%, e.g., at least 75%, or at least 100%of second perimeter P2. For some applications, first perimeter P1 doesnot equal second perimeter P2, and the perimeter of inferior firstlateral opening 34E is at least 60% of the lesser of first and secondperimeters P1 and P2.

For some applications, first stent-graft 20, when unconstrained in itsradially-expanded state, has an axial length of at least 10 cm, no morethan 40 cm, and/or between 10 and 40 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved.) For some applications,first stent-graft 20, when unconstrained in its radially-expanded state,has a greatest perimeter (at any axial location along the stent-graft)of at least 12 cm, no more than 21 cm, and/or between 12 and 21 cm.

For some applications, an axial distance D3 between the centers ofsuperior first lateral opening 34D and inferior first lateral opening34E is between 0 and 5 cm.

For some applications, such dimensions allow the first stent-graft to bepositioned such that (a) a proximal, radially larger, portion of thestent-graft, including the proximal end thereof, is disposed in theaorta downstream from the bifurcation with the left subclavian artery,at least partially in the upper part of the descending aorta, and (b) adistal, radially smaller, portion of the stent-graft, including thedistal end thereof, is disposed in the left common carotid artery, suchas described hereinbelow with reference to FIG. 9C. For someapplications, the proximal portion of the stent-graft has an averageperimeter that is greater than (e.g., between 5% and 15% greater than)an average perimeter of the portion of the aorta in which it is disposed(excluding expansion of the aorta due to the aneurysm, i.e., assumingthe aorta were healthy). For some applications, the distal portion ofthe stent-graft has an average perimeter that is greater than (e.g.,between 5% and 15% greater than) the average perimeter of the portion ofthe left common carotid artery in which it is disposed.

The Second Stent-Graft

In the configuration shown in FIG. 7, second covering element 42 andsecond support element 40 of second stent-graft 22 are shaped so as totogether define no lateral openings.

For some applications, as shown in FIG. 7, proximal end 46 of secondstent-graft 22 is outwardly flared in a proximal direction when thestent-graft is unconstrained in its radially-expanded state. Optionally,the stent-graft is additionally slightly indented radially inwardimmediately distal to the outward flare. Typically, covering element 42covers at least a distal portion of the outward flare. The flare enablessecure anchoring of the second stent-graft to the first stent-graft,such as described hereinbelow with reference to FIG. 9D. Alternatively,proximal end 46 is not flared, and second stent-graft instead has theconfiguration FIG. 1A or FIG. 1B. In this alternate configuration,covering element 42 typically does not fully cover proximal sub-portion70 (as shown in FIGS. 1A and 1B) of support element 40, thereby allowingblood flow through the stent-graft, as described hereinbelow withreference to FIG. 8. Optionally, proximal sub-portion 70 is flaredradially outward in a proximal direction at its proximal end.

For some applications, when second stent-graft 22 is unconstrained inits radially-expanded state, fourth perimeter P4 of second (distal) end48 of the second stent-graft is substantially greater than thirdperimeter P3 of first (proximal) end 46 of the second stent-graft, suchas at least 150% of P3, e.g., at least 200% or at least 300%. For someapplications, third perimeter P3 is at least 5.5 cm, no more than 17 cm,and/or between 5.5 and 17 cm. For some applications, fourth perimeter P4is at least 2.75 cm, no more than 6.3 cm, and/or between 2.75 and 6.3cm.

For some applications, second stent-graft 22, when unconstrained in itsradially-expanded state, has an axial length of at least 5 cm, no morethan 20 cm, and/or between 5 and 20 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved.) For some applications,second stent-graft 22, when unconstrained in its radially-expandedstate, has a greatest perimeter (at any axial location along thestent-graft) of at least 3 cm, no more than 6 cm, and/or between 3 and 6cm.

For some applications, such dimensions allow the second stent-graft tobe positioned such that (a) a proximal portion of the stent-graft,including the proximal end thereof, is disposed in the aorta in thefirst stent-graft, and (b) a distal portion of the stent-graft,including the distal end thereof, is disposed in the left common carotidartery, such as described hereinbelow with reference to FIG. 9D. Forsome applications, the proximal portion of the stent-graft has anaverage perimeter that is less than (e.g., between 30% and 70% lessthan) an average perimeter of the portion of the aortic arch in which itis disposed (excluding expansion of the aortic arch due to the aneurysm,i.e., assuming the aortic arch were healthy). For some applications, thedistal portion of the stent-graft has an average perimeter that isgreater than (e.g., between 5% and 15% greater than) the averageperimeter of the portion of the left common carotid artery in which itis disposed.

The Third Stent-Graft

In the configuration shown in FIG. 7, third covering element 52 andthird support element 50 of third stent-graft 24 are shaped so as totogether define third lateral opening 54 (typically, exactly one thirdlateral opening) through third stent-graft 24 when the third stent-graftis in its radially-expanded state.

For some applications, when third stent-graft 24 is unconstrained in itsradially-expanded state, sixth perimeter P6 of second (distal) end 58 ofthe third stent-graft is substantially greater than fifth perimeter P5of first (proximal) end 56 of the third stent-graft, such as at least150% of P3, e.g., at least 250% or 400%. For some applications, fifthperimeter P5 is at least 2.5 cm, no more than 6.3 cm, and/or between 2.5and 6.3 cm. For some applications, sixth perimeter P6 is at least 9.4cm, no more than 18.8 cm, and/or between 9.4 and 18.8 cm.

For some applications, when third stent-graft 24 is unconstrained in itsradially-expanded state, a perimeter of third lateral opening 54 is atleast 4.7 cm, no more than 14 cm, and/or between 4.7 and 14 cm, such asat least 6.3 cm, no more than 11 cm, and/or between 6.3 and 11 cm.

For some applications, when third stent-graft 24 is unconstrained in itsradially-expanded state, a perimeter of third lateral opening 54 is atleast 25%, e.g., at least 40%, or at least 60% of sixth perimeter P6,and/or at least 50%, e.g., at least 100%, or at least 150% of fifthperimeter P5.

For some applications, third stent-graft 24, when unconstrained in itsradially-expanded state, has an axial length of at least 8 cm, no morethan 30 cm, and/or between 8 and 30 cm. (The axial length is measuredalong a central longitudinal axis of the stent-graft, including inapplications in which the stent-graft is curved.) For some applications,third stent-graft 24, when unconstrained in its radially-expanded state,has a greatest perimeter (at any axial location along the stent-graft)of at least 12.5 cm, no more than 22 cm, and/or between 12.5 and 22 cm.

For some applications, such dimensions allow the third stent-graft to bepositioned such that (a) a proximal, radially smaller, portion of thestent-graft, including the proximal end thereof, is disposed in thebrachiocephalic artery, and (b) a distal, radially larger, portion ofthe stent-graft, including the distal end thereof, is disposed in theaorta upstream from the bifurcation with the brachiocephalic artery, atleast partially in the upper part of the ascending aorta, such asdescribed hereinbelow with reference to FIG. 9E. For some applications,the proximal portion of the stent-graft has an average perimeter that isgreater than (e.g., between 5% and 15% greater than) an averageperimeter of the portion of the brachiocephalic artery in which it isdisposed. For some applications, the distal portion of the stent-grafthas an average perimeter that is greater than (e.g., between 5% and 15%greater than) the average perimeter of the portion of the aorta in whichit is disposed (excluding expansion of the aorta due to the aneurysm,i.e., assuming the aorta were healthy).

The Fourth Stent-Graft

In the configuration shown in FIG. 7, fourth covering element 62 andfourth support element 60 of fourth stent-graft 26 are shaped so as totogether define no lateral openings.

Typically, proximal end 66 of fourth stent-graft 26 is outwardly flaredin a proximal direction, and distal end 68 is outwardly flared in adistal direction, when the stent-graft is unconstrained in itsradially-expanded state. Optionally, the stent-graft is additionallyslightly indented radially inward immediately distal to the proximaloutward flare, and immediately proximal to the distal outward flare.Typically, covering element 62 covers at least a distal portion of theproximal outward flare, and at least a proximal portion of the distaloutward flare. The flares enable secure anchoring of the fourthstent-graft to the first and third stent-grafts, such as describedhereinbelow with reference to FIG. 9G.

For some applications, when fourth stent-graft 26 is unconstrained inits radially-expanded state, seventh perimeter P7 of first (proximal)end 66 of the fourth stent-graft is approximately equal to eighthperimeter P8 of second (distal) end 68 of the fourth stent-graft, suchas within 20% of P6. For some applications, each of seventh perimeter P7and eighth perimeter P8 is at least 6.3 cm, no more than 12.6 cm, and/orbetween 6.3 and 12.6 cm.

For some applications, when fourth stent-graft 26 is unconstrained inits radially-expanded states, an axial length of fourth stent-graft 26is at least 3 cm, no more than 10 cm, and/or between 3 and 10 cm. Forsome applications, when fourth stent-graft 26 is unconstrained in itsradially-expanded state, a greatest perimeter of the fourth stent-graft(at any axial location along the stent-graft) is at least 3 cm, no morethan 9 cm, and/or between 3 and 9 cm.

For some applications, such dimensions allow the fourth stent-graft tobe positioned such that (a) a proximal portion of the stent-graft,including the proximal end thereof, is disposed in the aortic arch inthe first stent-graft, and (b) a distal portion of the stent-graft,including the distal end thereof, is disposed in the aortic arch in thethird stent-graft, such as described hereinbelow with reference to FIG.9G. For some applications, each of the proximal and distal portions ofthe stent-graft has an average perimeter that is less than (e.g.,between 30% and 70% less than) an average perimeter of the portion ofthe aortic in which they are disposed.

Additional Configuration Detail

For some applications, stent-grafts 20, 22, and 24 are configured (e.g.,heat-set) to have generally straight longitudinal axes whenunconstrained in their radially-expanded states, i.e., no forces areapplied to the stent-grafts by a delivery tool, walls of a blood vessel,or otherwise. The stent-grafts typically assumed curved shapes whenplaced in respective blood vessels because of the force applied to thestent-grafts by the walls of the blood vessels, such as shown in FIGS.9C-G.

For other applications, stent-grafts 20, 22, and 24 are configured(e.g., heat-set) to have generally curved longitudinal axes whenunconstrained in their radially-expanded states, i.e., no forces areapplied to the stent-grafts by a delivery tool, walls of a blood vessel,or otherwise. This curvature may help properly position the stent-graftswith respect to one another, such as shown in FIGS. 7 and 9C-G. Thisconfiguration is similar to the curved configuration shown in FIG. 1B.For some applications, at least one the stent-grafts is generallystraight, while at least another one of the stent-grafts is generallycurved.

Typically, first and second stent-grafts 20 and 22 are not fixed to oneother when they are in their radially-compressed states. Likewise,first, second, and third stent-grafts 20, 22, and 24 are typically notfixed to one other when they are in their radially-compressed states.Furthermore, first, second, third, and fourth stent-grafts 20, 22, 24,and 26 are typically not fixed to one other when they are in theirradially-compressed states. In other words, the stent-grafts areinitially provided as separate, non-connected components, as shown inFIG. 4 (although they are typically initially positioned in outertube(s) of delivery tool(s), as described hereinbelow), which aretypically assembled in situ. Typically, first and second coveringelement 32 and 42 are not fixed to one other when they are in theirradially-compressed states. Likewise, first, second, and third coveringelement 32, 42, and 52 are typically not fixed to one other when first,second, and third stent-grafts 20, 22, and 24 are in theirradially-compressed states. Furthermore, first, second, third, andfourth covering elements 32, 42, 52, and 62 are typically not fixed toone other when first, second, third, and fourth stent-grafts 20, 22, 24,and 26 are in their radially-compressed states.

For some applications, one or more (e.g., all) of the lateral openingsare circumscribed by respective generally annular structural stentelements of the support elements.

Assembly of the Stent-Grafts

FIG. 8 is a schematic illustration of multi-component stent-graft system10, having the configuration described with reference to FIG. 7, in anassembled state, in accordance with an application of the presentinvention. As mentioned above, such assembly is typically performed insitu during an implantation procedure, but such assembly may also beperformed ex vivo. First, second, third, and fourth stent-grafts 20, 22,24, and 26 are shown in FIG. 8 in their radially-expanded states.

Second stent-graft 22 is configured to be disposed through superiorfirst lateral opening 34D, such that a portion (e.g., the flaredportion) of the second stent-graft is disposed within first stent-graft20, and a portion of the second stent-graft is disposed outside of thefirst stent-graft. The first and second stent-grafts are configured suchthat second covering element 42 forms a blood-impervious seal with firstcovering element 32 around superior first lateral opening 34D, when thesecond stent-graft is thus disposed through the superior first lateralopening, and first and second stent-grafts 20 and 22 are in theirradially-expanded states. The first and second stent-grafts are securelyanchored to each other. The blood-impervious seal is typically formedbecause support element 30 of the first stent-graft is configured tohaving a resting perimeter that is greater than the perimeter of thesuperior first lateral opening, such that the distal inferior firstlateral opening squeezes the second stent-graft when the secondstent-graft expands.

Alternatively, for some applications in which second stent-graft is notflared, when second stent-graft 22 is disposed through first superiorfirst lateral opening 34D and first and second stent-grafts 20 and 22are in their radially-expanded states, a proximal portion of secondsupport element 40 is disposed within first stent-graft 20, and secondcovering element 42 does not fully cover this proximal portion, therebyallowing blood flow through the first stent-graft (i.e., the secondcovering element does not fully cover proximal sub-portion 70), such asshown in FIG. 2. (Optionally, proximal sub-portion 70 is flared radiallyoutward in a proximal direction at its proximal end.) Typically, atleast a distal-most portion of this proximal portion is covered bysecond covering element 42, in order to form the above-mentionedblood-impervious seal with first covering element 32. Thus, secondcovering element 42 may be configured to cover a distal sub-portion, andnot a proximal sub-portion, of this proximal portion. For some of theseapplications, second support element 40 is configured to extend intofirst stent-graft 20 a distance sufficient to help anchor the secondstent-graft to the first stent-graft, such as at least 3 cm, no morethan 10 cm, and/or between 3 and 10 cm. For some applications, theproximal portion has a perimeter that is sufficient to apply aradially-outward force against an inner surface of a wall of firststent-graft 20, in order to help anchor the second stent-graft to thefirst stent-graft. For example, an axial portion of the proximal portionhaving a length of at least 5 cm may have a perimeter that is at least10% greater than a perimeter of a portion of the first stent-graft inwhich the proximal portion is disposed. Typically, second stent-graft 22is deployed such that proximal portion 82 extends into the firststent-graft in a proximal direction from first lateral opening 34, suchas shown in FIG. 2.

Proximal and distal ends 66 and 68 fourth stent-graft 26 are configuredto be disposed through inferior first lateral opening 34E of firststent-graft 20 and third lateral opening 54 of third stent-graft 24,respectively, such that:

-   -   a proximal portion (e.g., the proximal flared portion) of the        fourth stent-graft is disposed within first stent-graft 20,    -   a distal portion (e.g., the distal flared portion) of the fourth        stent-graft is disposed within third stent-graft 24, and    -   a middle portion of the fourth stent-graft is disposed outside        of the first and third stent-grafts.

The first and fourth stent-grafts are configured such that fourthcovering element 62 forms a blood-impervious seal with first coveringelement 32 around inferior first lateral opening 34E, when the proximalend of fourth stent-graft is thus disposed through the inferior firstlateral opening 34E, and first and fourth stent-grafts 20 and 26 are intheir radially-expanded states. The first and fourth stent-grafts aresecurely anchored to each other. Similarly, the third and fourthstent-grafts are configured such that fourth covering element 62 forms ablood-impervious seal with third covering element 52 around thirdlateral opening 54, when distal end of the fourth stent-graft is thusdisposed through the third lateral opening, and third and fourthstent-grafts 24 and 26 are in their radially-expanded states. The thirdand fourth stent-grafts are securely anchored to each other.

For some applications, a method is provided that comprises assemblingfirst, second, third, and fourth stent-grafts 20, 22, 24, and 26, asdescribed hereinabove with reference to FIG. 8, either in situ or exvivo.

An Exemplary Deployment Procedure for the Configuration in which theFirst Stent-Graft has Two Lateral Openings

Reference is made to FIGS. 9A-G, which are schematic illustrations of anexemplary transluminal delivery procedure for implanting multi-componentstent-graft system 10, as configured in FIGS. 7 and 8, in accordancewith an application of the present invention. In this exemplaryprocedure, first, second, and fourth stent-grafts 20, 22, and 26 ofsystem 10 are transvascularly (typically percutaneously) introduced intoaortic arch 100, typically via one of the iliac arteries, while thestent-grafts are positioned in one or more outer tubes of a deliverytool in their radially-compressed states. Third stent-graft 24 istypically deployed via a right subclavian artery.

Deployment of the First Stent-Graft

First stent-graft 20 is initially positioned in its radially-compressedstate within outer tube 130 of a delivery tool, typically near distalend 132 of the outer tube (e.g., such that at least one end ofstent-graft 20 is within a distance of distal end 132, which distanceequals the sum of 2 cm and an axial length of the first stent-graft).The exemplary procedure begins with the advancing of guidewire 120 updescending aorta 102 and into a first one of the branches of the aorticarch, such as left common carotid artery 104. Outer tube 130 is advancedover guidewire 120, until first stent-graft 20 is partially disposed inleft common carotid artery 104, partially disposed in aortic arch 100,and partially disposed an upper part of descending aorta 102, as shownin FIG. 9A. The guidewire is withdrawn, leaving outer tube 130 in place.

As shown in FIGS. 9B and 9C, the first stent-graft is held in place asouter tube 130 is withdrawn, thereby delivering the first stent-graftfrom the outer tube. Optionally, techniques for holding the firststent-graft in place may be used that are described hereinbelow withreference to FIGS. 10 and 11A-E or FIGS. 12A-C. First stent-graft 20typically self-expands, until it assumes its radially-expanded state,upon reaching its maximum unconstrained size, and/or being constrainedfrom further expansion by the wall of the blood vessels. Alternatively,the first stent-graft (and/or the second, third, and/or fourthstent-grafts, as described hereinbelow) is delivered using anover-the-wire (OTW) approach, in which the guidewire is left in placeuntil the stent-graft is expanded, and thereafter the guidewire iswithdrawn. FIG. 9B shows the first stent-graft partially released fromouter tube 130 (and thus partially expanded), and FIG. 9C shows thefirst stent-graft fully released from the outer tube (and thus fullyexpanded).

A proximal portion 150 of first stent-graft 20, including proximal end36, is positioned in the upper part of descending aorta 102, a middleportion 152 of first stent-graft 20 is positioned in aortic arch 100,and a distal portion 154 of first stent-graft 20, including distal end38, is positioned in left common carotid artery 104. Superior firstlateral opening 34D faces toward and is aligned with left subclavianartery 105, and inferior first lateral opening 34E is disposed in aorticarch 100 facing upstream, generally toward ascending aorta 101, in avicinity of the bifurcation of aortic arch 100 and left common carotidartery 104. For some applications, proper rotational alignment and/oraxial orientation of the first lateral openings is achieved usingfluoroscopy. For example, first stent-graft 20 may comprise one or moreradiopaque markers in a vicinity (e.g., on a periphery of) the firstlateral openings.

Deployment of the Second Stent-Graft

Also as shown in FIG. 9C, second stent-graft 22 is initially positionedin its radially-compressed state within an outer tube of a delivery tool(either the same outer tube 130 used to deploy the first stent-graft, ora second outer tube), typically near distal end 132 of the outer tube(e.g., such that at least one end of stent-graft 22 is within a distanceof distal end 132, which distance equals the sum of 2 cm and an axiallength of the first stent-graft). A guidewire (either the same guidewire120 used to deploy the first stent-graft, or a second guidewire) isadvanced up descending aorta 102, through a proximal portion of firststent-graft 20, out of superior first lateral opening 34D, and into leftsubclavian artery 105. Outer tube 130 is advanced over guidewire 120,until second stent-graft 22 is partially disposed in left subclavianartery 105 and partially disposed within radially-expanded firststent-graft 20 in aortic arch 100. The guidewire is withdrawn, leavingouter tube 130 in place.

As shown in FIG. 9D, the second stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the second stent-graft fromthe outer tube. Optionally, techniques for holding the secondstent-graft in place may be used that are described hereinbelow withreference to FIGS. 10 and 11A-E or FIGS. 12A-C. Second stent-graft 22typically self-expands, until it assumes its radially-expanded state,upon reaching its maximum unconstrained size, and/or being constrainedfrom further expansion by the wall of the blood vessels.

A proximal portion of second stent-graft 22, including proximal end 46,is positioned within first stent-graft 20 in aortic arch 100, and adistal portion of second stent-graft 22, including distal end 48, ispositioned in left subclavian artery 105.

Second stent-graft 22 is thus adapted for transluminal delivery in itsradially-compressed state through a portion of first stent-graft 20 andone of first lateral openings 34 (e.g., superior first lateral opening34D), while the first stent-graft is in its radially-expanded state.

Deployment of the Third Stent-Graft

As also shown in FIG. 9D, third stent-graft 24 is initially positionedin its radially-compressed state within an outer tube 230 of a deliverytool (typically separate from outer tube 130 used to deploy the firstand/or second stent-grafts), typically near a distal end 232 of theouter tube (e.g., such that at least one end of stent-graft 24 is withina distance of distal end 232, which distance equals the sum of 2 cm andan axial length of the third stent-graft). A guidewire 220 (typicallyseparate from guidewire 120 used to deploy the first and/or secondstent-grafts) is advanced down a right subclavian artery 108 andbrachiocephalic artery 103 into the upper part of ascending aorta 101.Outer tube 230 is advanced over guidewire 220, until third stent-graft24 is partially disposed in brachiocephalic artery 103 and partiallydisposed in the upper part of ascending aorta 101. The guidewire iswithdrawn, leaving outer tube 130 in place.

As shown in FIG. 9E, the third stent-graft is held in place as outertube 230 is withdrawn, thereby delivering the third stent-graft from theouter tube. Optionally, techniques for holding the third stent-graft inplace may be used that are described hereinbelow with reference to FIGS.10 and 11A-E or FIGS. 12A-C. Third stent-graft 24 typicallyself-expands, until it assumes its radially-expanded state, uponreaching its maximum unconstrained size, and/or being constrained fromfurther expansion by the wall of the blood vessels.

A proximal portion of third stent-graft 24, including proximal end 56,is positioned within brachiocephalic artery 103, and a distal portion ofthird stent-graft 24, including distal end 58, is positioned in theupper part of ascending aorta 101. Third lateral opening 54 is disposedin aortic arch 100 facing downstream, generally toward descending aorta102, in a vicinity of the bifurcation of aortic arch 100 andbrachiocephalic artery 103, such that third lateral opening 54 faces andaligned with inferior first lateral opening 34E of first stent-graft 20.

Alternatively, third stent-graft 24 is deployed prior to deployment offirst stent-graft 20 (in which case, typically also prior to deploymentof second stent-graft 22).

Deployment of the Fourth Stent-Graft

As shown in FIG. 9F, fourth stent-graft 26 is initially positioned inits radially-compressed state within an outer tube of a delivery tool(either the same outer tube 130 used to deploy the first and/or secondstent-grafts, or an additional outer tube), typically near distal end132 of the outer tube (e.g., such that at least one end of stent-graft26 is within a distance of distal end 132, which distance equals the sumof 2 cm and an axial length of the first stent-graft). A guidewire(either the same guidewire 120 used to deploy the first and/or secondstent-grafts or an additional guidewire) is advanced up descending aorta102, through a proximal portion of first stent-graft 20, and out ofinferior first lateral opening 34E. The guidewire is advanced throughaortic arch 100 between inferior first lateral opening 34E of firststent-graft 20 and third lateral opening 54 of third stent-graft 24.Outer tube 130 is advanced over guidewire 120, until fourth stent-graft26 is partially disposed in third stent-graft 24, partially disposed infirst stent-graft 20, and partially disposed in aortic arch 100 betweenthe first and third stent-grafts. The guidewire is withdrawn, leavingouter tube 130 in place.

As shown in FIG. 9G, the fourth stent-graft is held in place as outertube 130 is withdrawn, thereby delivering the fourth stent-graft fromthe outer tube. Optionally, techniques for holding the fourthstent-graft in place may be used that are described hereinbelow withreference to FIGS. 10 and 11A-E or FIGS. 12A-C. Fourth stent-graft 26typically self-expands, until it assumes its radially-expanded state,upon reaching its maximum unconstrained size, and/or being constrainedfrom further expansion by inferior first lateral opening 34E, thirdlateral opening 54, and/or the wall of aortic arch 100.

A proximal portion of fourth stent-graft 26, including proximal end 66,is positioned within first stent-graft 20, a distal portion of fourthstent-graft 26, including distal end 68, is positioned within thirdstent-graft 24, and a middle portion of fourth stent-graft 26 ispositioned in aortic arch 100.

Fourth stent-graft 26 is thus adapted for transluminal delivery in itsradially-compressed state through a portion of first stent-graft 20 andone of first lateral openings 34 (e.g., inferior first lateral opening34E), and through third lateral opening 54 and a portion of thirdstent-graft 24, while the first and third stent-grafts are in theirradially-expanded state. Alternatively, fourth stent-graft 26 isdeployed through right subclavian artery 108 and brachiocephalic artery103, and through fourth stent-graft 26 (configuration not shown).

As can be seen in FIG. 9G, upon deployment of all four stent-grafts,multi-component stent-graft system 10 defines a blood-flow path fromascending aorta 101, over aortic arch 100, and to descending aorta 102.Multi-component stent-graft system 10 additionally provides blood-flowpaths to the three branches of the aortic arch: brachiocephalic artery103, left common carotid artery 104, and left subclavian artery 105.

Reference is now made to FIG. 9H, which is a schematic illustration ofan alternative configuration and deployment of stent-graft system 10, inaccordance with an application of the present invention. In thisdeployment, first and second stent-grafts 20 and 22 are configured asdescribed hereinabove with reference to FIGS. 7 and 8, and are deployedas described hereinabove with reference to FIGS. 9A-D. Third stent-graft24 is configured similarly to the configuration thereof describedhereinabove with reference to FIGS. 7 and 8, and is deployed through aportion of first stent-graft 20 and inferior first lateral opening 34E,such that third stent-graft 24 is disposed in aortic arch 100 and/or theupper part of ascending aorta 101, and third lateral opening 54 facestoward and is aligned with brachiocephalic artery 103. Fourthstent-graft 26 is configured as described hereinabove with reference toFIGS. 4 and 5, and is deployed through a portion of first stent-graft20, a portion of third stent-graft 24, and third lateral opening 54 intobrachiocephalic artery 103.

In yet another alternative deployment (not shown), first and secondstent-grafts 20 and 22 are configured as described hereinabove withreference to FIGS. 7 and 8, and are deployed as described hereinabovewith reference to FIGS. 9A-D. Third stent-graft 24 is configured asdescribed hereinabove with reference to FIGS. 1A-2, and is deployedthrough a portion of first stent-graft 20 and inferior first lateralopening 34E as described hereinabove with reference to FIGS. 3G-I,mutatis mutandis. Optionally, fourth stent-graft 26 is configured asdescribed hereinabove with reference to FIGS. 1A-2, and is deployedthrough a portion of first stent-graft 20, a portion of thirdstent-graft 24, and third lateral opening 54 as described hereinabovewith reference to FIGS. 3J-L, mutatis mutandis.

Delivery Tools

As mentioned above, for some applications of the present invention, twoor more of stent-grafts 20, 22, 24, and 26 are deployed from the sameouter tube 130 of a delivery tool 300. For some such applications, thetwo or more stent-grafts are initially positioned at respective axialsites within outer tube 130, in their radially-compressed states withoutbeing fixed to each other.

Reference is made to FIG. 10, which is a schematic illustration of firstand second stent-grafts 20 and 24 initially positioned within outer tube130 of a delivery tool 300, in accordance with an application of thepresent invention. First and second stent-grafts 20 and 22 are initiallypositioned at respective axial sites within outer tube 130, in theirradially-compressed states without being fixed to each other. Typically,first and second stent-grafts 20 and 22 are initially positioned in theouter tube such that at least one end of one of the stent-grafts (forexample, first stent-graft 20, as shown in FIG. 10) is within a distanceof distal end 132 of outer tube 130, which distance equals the sum of 2cm and an axial length of first stent-graft 20. Additional stent-grafts(e.g., third stent-graft 24 and/or fourth stent-graft 26) may also beinitially positioned at respective axial sites within outer tube 130.

For some applications, delivery tool 300 is shaped so as to define firstand second stopper elements 310 and 312, which are configured andinitially positioned to prevent movement of first and secondstent-grafts 20 and 22, respectively, in a proximal direction away fromdistal end 132 of outer tube 130. For some applications, as shown inFIG. 10, delivery tool 300 further comprises an inner longitudinalmember 314, which is initially positioned such that first and secondportions 316 and 318 thereof are within first and second stent-grafts 20and 22, respectively, and inner longitudinal member 314 is shaped so asto define first and second stopper elements 310 and 312. The stopperelements are shaped and/or sized to prevent passage thereof through thestent-grafts when in their radially-compressed states. If additionalstent-grafts are also positioned in the outer tube, the innerlongitudinal member is typically shaped so as to define additionalrespective stopper elements. Typically, inner longitudinal member 314 isshaped so as to define a lumen therethrough (not shown), through whichguidewire 120 may pass, as shown in a number of the figures describedhereinabove.

Reference is made to FIGS. 11A-E, which are schematic illustrationsshowing the deployment of first and second stent-grafts 20 and 22 usingdeployment tool 300 configured as described hereinabove with referenceto FIG. 10, in accordance with an application of the present invention.Although these illustrations show the deployment of first and secondstent-grafts 20 and 22 in the configuration described hereinabove withreference to FIGS. 1A-C and 2, this deployment technique may also beused to deploy additional stent-grafts (such as third and/or fourthstent-grafts 24 and 26), and/or stent-grafts with other configurations,including the other configurations described hereinabove with referenceto FIGS. 4-5 and FIGS. 7-8, or other stent-grafts known in the art.

The exemplary procedure begins with the advancing of guidewire 120 updescending aorta 102 and into a first one of the branches of aortic arch100, such as left subclavian artery 105, as shown in FIG. 11A.

As shown in FIG. 11B, first stent-graft 20 is initially positioned inits radially-compressed state within outer tube 130 of delivery tool300, typically near distal end 132 of the outer tube, surrounding firstportion 316 of inner longitudinal member 314. Second stent-graft 22 isinitially positioned in its radially-compressed state within outer tube130, typically near a proximal end of the first stent-graft, surroundingsecond portion 318. First stopper elements 310 is positioned proximallyadjacent to first stent-graft 20 (and distal to second stent-graft 22),and second stopper element 312 is positioned proximally adjacent tosecond stent-graft 22. For applications in which additional stent-graftsare also deployed, additional stopper elements are typically providedand positioned in like manner.

Outer tube 130 is advanced over guidewire 120, until first stent-graft20 is partially disposed in left subclavian artery 105 and partiallydisposed in the upper part of descending aorta 102. The guidewire iswithdrawn, leaving outer tube 130 in place.

As shown in FIG. 11C, as outer tube 130 is withdrawn, first stent-graft20 is held in place by first stopper element 310, which preventsmovement of the first stent-graft in a proximal direction. Firststent-graft 20 typically self-expands, until it assumes itsradially-expanded state, upon reaching its maximum unconstrained size,and/or being constrained from further expansion by the wall of the bloodvessels.

Guidewire 120 is advanced up descending aorta 102, through a proximalportion of first-stent-graft 20, out of first lateral opening 34, andinto a second one of the branches of aortic arch 100, such as leftcommon carotid artery 104, as shown in FIG. 11D.

Outer tube 130 is advanced over guidewire 120, until second stent-graft22 is partially disposed in left common carotid artery 104 and partiallydisposed within radially-expanded first stent-graft 20 in the upper partof descending aorta 102, as shown in FIG. 11E. First portion 316 ofinner longitudinal member 314 is disposed in left common carotid artery104, further up the artery than the distal end of second stent-graft 22.When outer tube 130 is subsequently withdrawn (not shown), secondstent-graft 22 is held in place by second stopper element 312, whichprevents movement of the second stent-graft in a proximal direction.Deployment continues as described hereinabove.

Reference is made to FIGS. 12A-C, which are schematic illustrations ofanother configuration of delivery tool 300, in accordance with anapplication of the present invention. Except as described below, thisconfiguration of the delivery tool is generally similar to theconfiguration described hereinabove with reference to FIG. 10. As in theconfiguration described hereinabove, first and second stent-grafts 20and 22 are initially positioned at respective axial sites within outertube 130, in their radially-compressed states without being fixed toeach other, as shown in FIG. 12A. Additional stent-grafts (e.g., thirdstent-graft 24 and/or fourth stent-graft 26) may also be initiallypositioned at respective axial sites within out tube 130. Innerlongitudinal member 314 is initially positioned such that first andsecond portions 316 and 318 thereof are within first and secondstent-grafts 20 and 22, respectively.

Inner longitudinal member 314 is shaped so as to define a stopperelement 330. The stopper element is shaped and/or sized to preventpassage thereof through the stent-grafts when in theirradially-compressed states, but to be withdrawable in the proximaldirection through the stent-graft(s) positioned proximal to the stopperelement, when the stent-grafts are in their radially-compressed states.For example, stopper element 330 is configured to be withdrawable in theproximal direction through second stent-graft 22, and after being thuswithdrawn, to prevent movement of second stent-graft 22 in the proximaldirection. For some applications, an inner surface of outer tube 130 isshaped so as to define at least one pusher element 320, which isconfigured to prevent movement of at least one of the first and secondstent-grafts in the proximal direction, but to allow advancement of thestent-grafts in the distal direction with respect to the outer tube. Ifadditional stent-grafts are also positioned in the outer tube, the innerlongitudinal member is optionally shaped so as to define one or morespacer elements 332, which are configured to maintain adjacentstent-grafts slightly axially spaced apart from each other, and to slidebidirectionally through the additional stent-grafts.

FIG. 12A shows the stent-grafts in their initial positions in outer tube130. As shown in FIG. 12B, after first stent-graft 20 has beenpositioned at a desired anatomical location, outer tube 130 is withdrawnin a proximal direction (downward in the figure), while holding innerlongitudinal member 314 stationary. Stopper element 330 preventsproximal movement of the first stent-graft, causing the firststent-graft to be deployed from outer tube 130, and to self-expandaround first portion 316 of inner longitudinal member 314. The secondset of one or more pusher elements 320 prevents proximal movement ofsecond stent-graft 22, so that the second stent-graft is now positionednear distal end 132 of outer tube 130, still surrounding second portion318 of inner longitudinal member 314.

As shown in FIG. 12C, inner longitudinal member 314 is withdrawn in aproximal direction. Pusher element(s) 320 prevent proximal motion ofsecond stent-graft 22, while stopper element 330 of inner longitudinalmember 314 slides proximally through second stent-graft 22. As a result,the second stent-graft remains positioned near distal end 132, and nowsurrounds first portion 316, rather than second portion 318, of innerlongitudinal member 314. The second stent-graft is now ready fordeployment. This technique obviates the need for first portion 316 ofinner longitudinal member 314 to be extended up a target blood vessel,such as shown in FIG. 11E.

In some applications of the present invention, a kit is provided thatcomprises two or more of stent-grafts 20, 22, 24, and/or 26.

For some applications, one or more of stent-grafts 20, 22, 24, and/or 26comprise one or more anchoring elements, such as barbs, that extendradially outwardly when the stent-grafts assume their radially-expandedstates. The anchoring elements anchor the prosthesis to a vascular wall,helping prevent dislodgement.

Although stent-grafts 20, 22, 24, and 26 have sometimes been describedhereinabove as being deployed in an area of the thoracic aorta, thestent-grafts may, for some applications, also be deployed in anothermain body lumen and one or more of its branching body lumens, such asanother main blood vessel and one or more of its branching bloodvessels. For example:

-   -   the first stent-graft may extend from the external carotid        artery into the internal carotid artery, such that the first        lateral opening faces the common carotid artery, and the second        stent-graft may extend from the external carotid artery, through        the first lateral opening, and into the common carotid artery;        or    -   the first stent-graft may extend from the external iliac artery        into the internal iliac artery, such that the first lateral        opening faces the common iliac artery, and the second        stent-graft may extend from the external iliac artery, through        the first lateral opening, and into the common iliac artery.

The scope of the present invention includes embodiments described in thefollowing applications, which are assigned to the assignee of thepresent application and are incorporated herein by reference. In anembodiment, techniques and apparatus described in one or more of thefollowing applications are combined with techniques and apparatusdescribed herein:

-   -   PCT Application PCT/IL2008/000287, filed Mar. 5, 2008, which        published as PCT Publication WO 2008/107885 to Shalev et al.    -   U.S. application Ser. No. 12/529,936, which published as US        Patent Application Publication 2010/0063575 to Shalev et al.    -   U.S. Provisional Application 60/892,885, filed Mar. 5, 2007    -   U.S. Provisional Application 60/991,726, filed Dec. 2, 2007    -   U.S. Provisional Application 61/219,758, filed Jun. 23, 2009    -   U.S. Provisional Application 61/221,074, filed Jun. 28, 2009    -   PCT Application PCT/IB2010/052861, filed Jun. 23, 2010    -   a PCT application filed Jul. 14, 2010, entitled, “Sideport        engagement and sealing mechanism for endoluminal stent-grafts”    -   PCT Application PCT/IL2010/000917, filed Nov. 4, 2010

It will be appreciated by persons skilled in the art that the presentinvention is not limited to what has been particularly shown anddescribed hereinabove. Rather, the scope of the present inventionincludes both combinations and subcombinations of the various featuresdescribed hereinabove, as well as variations and modifications thereofthat are not in the prior art, which would occur to persons skilled inthe art upon reading the foregoing description.

1. Apparatus comprising a multi-component stent-graft system, whichcomprises: a first generally tubular stent-graft, which is shaped so asto define a first lateral opening when in a radially-expanded state; asecond generally tubular stent-graft, which is shaped so as to define asecond lateral opening when in a radially-expanded state, wherein thefirst and second stent-grafts are configured such that the secondstent-graft forms a blood-impervious seal with the first stent-graftaround the first lateral opening when the second stent-graft is disposedtherethrough, and the first and the second stent-grafts are in theirradially-expanded states; and a third generally tubular stent-graft,which is configured to assume a radially-expanded state, wherein thesecond and the third stent-grafts are configured such that the thirdstent-graft forms a blood-impervious seal with the second stent-graftaround the second lateral opening when the third stent-graft is disposedtherethrough, and the second and third stent-grafts are in theirradially-expanded states.
 2. The apparatus according to claim 1, whereinthe first stent-graft comprises a first generally tubular supportelement and a first covering element attached to the first supportelement so as to at least partially cover the first support element, andthe first covering element and the first support element are shaped soas to together define the first lateral opening through the firststent-graft when the first stent-graft is in its radially-expandedstate, wherein the second stent-graft comprises a second generallytubular support element and a second covering element attached to thesecond support element so as to at least partially cover the secondsupport element, and the second covering element and the second supportelement are shaped so as to together define the second lateral openingthrough the second stent-graft when the second stent-graft is in itsradially-expanded state, and the first and the second stent-grafts areconfigured such that the second covering element forms theblood-impervious seal with the first covering element around the firstlateral opening when the second stent-graft is disposed therethrough,and the first and the second stent-grafts are in their radially-expandedstates, and wherein the third stent-graft comprises a third generallytubular support element and a third covering element attached to thethird support element so as to at least partially cover the thirdsupport element, and the second and the third stent-grafts areconfigured such that the third covering element forms theblood-impervious seal with the second covering element around the secondlateral opening when the third stent-graft is disposed therethrough, andthe second and third stent-grafts are in their radially-expanded states.3. The apparatus according to claim 2, wherein the first, the second,and the third covering elements are not fixed to one another when thefirst, the second, and the third stent-grafts are in theirradially-compressed states.
 4. The apparatus according to claim 2,wherein, when the third stent-graft is disposed through the secondlateral opening and the second and the third stent-grafts are in theirradially-expanded states: a proximal portion of the third supportelement is disposed within the second stent-graft, and the thirdcovering element does not fully cover the proximal portion of the thirdsupport element, thereby allowing blood flow through the secondstent-graft.
 5. The apparatus according to claim 1, wherein the secondstent-graft is configured to transition, without inverting, from aradially-compressed state to its radially-expanded state.
 6. Theapparatus according to claim 1, wherein the third stent-graft isconfigured to transition, without inverting, from a radially-compressedstate to its radially-expanded state.
 7. The apparatus according toclaim 1, wherein the first, the second, and the third stent-grafts arenot fixed to one other when in their radially-compressed states.
 8. Theapparatus according to claim 1, wherein the third stent-graft is adaptedfor transluminal delivery in a radially-compressed state through,sequentially, (a) a portion of the first stent-graft, (b) the firstlateral opening, (c) a portion of the second stent-graft, and (d) thesecond lateral opening, while the first and the second stent-grafts arein their radially-expanded states.
 9. The apparatus according to claim1, wherein the third stent-graft is shaped so as to define a thirdlateral opening when in its radially-expanded state, wherein thestent-graft system further comprises a fourth generally tubularstent-graft, which is configured to assume a radially-expanded state,and wherein the third and the fourth stent-grafts are configured suchthat the fourth stent-graft forms a blood-impervious seal with the thirdstent-graft around the third lateral opening when the fourth stent-graftis disposed therethrough, and the third and the fourth stent-grafts arein their radially-expanded states.
 10. The apparatus according to claim9, wherein the third covering element and the third support element areshaped so as to together define the third lateral opening through thethird stent-graft when the third stent-graft is in its radially-expandedstate, wherein the fourth stent-graft comprises a fourth generallytubular support element and a fourth covering element, which is attachedto the fourth support element so as to at least partially cover thefourth support element, and wherein the third and the fourthstent-grafts are configured such that the fourth covering element formsthe blood-impervious seal with the third covering element around thethird lateral opening when the fourth stent-graft is disposedtherethrough, and the third and the fourth stent-grafts are in theirradially-expanded states.
 11. The apparatus according to claim 10,wherein the fourth covering element and the fourth support element arenot shaped so as to together define any lateral openings through thefourth stent-graft when the fourth stent-graft is in itsradially-expanded state.
 12. The apparatus according to claim 9, whereinthe first, the second, the third, and the fourth stent-grafts areconfigured for transluminal delivery for transport to respective siteswithin a body lumen when in radially-compressed states, and wherein thefourth stent-graft is adapted for transluminal delivery in itsradially-compressed state through, sequentially, (a) a portion of thefirst stent-graft, (b) the first lateral opening, (c) a portion of thesecond stent-graft, (d) the second lateral opening, (e) a portion of thethird stent-graft, and (f) the third lateral opening, while the first,the second, and the third stent-grafts are in their radially-expandedstates.
 13. The apparatus according to claim 1, wherein (a) a proximalportion of the first stent-graft, including a proximal end of thefirst-stent-graft, is configured to be positioned in a proximal portionof a main blood vessel, (b) a distal portion of the first stent-graft,including a distal end of the first stent-graft, is configured to bepositioned in a branching blood vessel that branches from the main bloodvessel, and (c) the first stent-graft is configured such that a firstlateral opening defined by the first stent-graft is disposed within themain blood vessel facing toward a distal portion of the main bloodvessel, and wherein the second stent-graft is configured to be disposedpartially in the distal portion of the main blood vessel.
 14. Theapparatus according to claim 1, wherein the first stent-graft is shapedso as to define exactly one first lateral opening when the firststent-graft is in its radially-expanded state.
 15. Apparatus comprisinga multi-component stent-graft system, which comprises: a first generallytubular stent-graft, which, when unconstrained in a radially-expandedstate: (a) defines a first lateral opening, and (b) has a firstperimeter of a first end thereof that equals at least 200% of a secondperimeter of a second end thereof; and a second generally tubularstent-graft, which is configured to assume a radially-expanded state,wherein the first and the second stent-grafts are configured such thatthe second stent-graft forms a blood-impervious seal with the firststent-graft around the first lateral opening when the second stent-graftis disposed therethrough, and the first and second stent-grafts are intheir radially-expanded states.
 16. The apparatus according to claim 15,wherein the first stent-graft comprises a first generally tubularsupport element and a first covering element attached to the firstsupport element so as to at least partially cover the first supportelement, and the first covering element and the first support elementare shaped so as to together define the first lateral opening throughthe first stent-graft when the first stent-graft is in itsradially-expanded state, and wherein the second stent-graft comprises asecond generally tubular support element and a second covering elementattached to the second support element so as to at least partially coverthe second support element, and the first and the second stent-graftsare configured such that the second covering element forms theblood-impervious seal with the first covering element around the firstlateral opening when the second stent-graft is disposed therethrough,and the first and the second stent-grafts are in their radially-expandedstates.
 17. The apparatus according to claim 15, wherein the firstperimeter equals at least 250% of the second perimeter.
 18. Theapparatus according to claim 17, wherein the first perimeter equals atleast 400% of the second perimeter.
 19. The apparatus according to claim15, wherein the first perimeter is between 7.5 and 15 cm, and the secondperimeter is between 2.5 and 5.7 cm.
 20. The apparatus according toclaim 15, wherein, when the first stent-graft is unconstrained in itsradially-expanded state, a perimeter of the first lateral opening is atleast 40% of the first perimeter.
 21. The apparatus according to claim15, wherein, when the first stent-graft is unconstrained in itsradially-expanded state, a perimeter of the first lateral opening is atleast 60% of the second perimeter.
 22. The apparatus according to claim15, wherein the second stent-graft is configured to transition, withoutinverting, from a radially-compressed state to its radially-expandedstate.
 23. The apparatus according to claim 15, wherein the firstlateral opening includes a superior first lateral opening and aninferior first lateral opening, wherein the first stent-graft is shapedso as to define the superior first lateral opening facing in a firstradial direction, and the inferior first lateral opening facing a secondradial direction generally opposite the first radial direction, andwherein the first and the second stent-grafts are configured such thatthe second stent-graft forms the blood-impervious seal with the firststent-graft around one of the superior and inferior first lateralopenings when the second stent-graft is disposed therethrough, and thefirst and second stent-grafts are in their radially-expanded states. 24.The apparatus according to claim 23, wherein the first and the secondstent-grafts are configured such that the second stent-graft forms theblood-impervious seal with the first covering element around thesuperior first lateral opening when the second stent-graft is disposedtherethrough, and the first and second stent-grafts are in theirradially-expanded states.
 25. The apparatus according to claim 15,wherein the first stent-graft is shaped so as to define exactly onefirst lateral opening when the first stent-graft is in itsradially-expanded state.
 26. Apparatus comprising a multi-componentstent-graft system, which comprises: a first stent-graft, which isshaped so as to define, when in a radially-expanded state, proximal anddistal superior first lateral openings facing in a first radialdirection, and a distal inferior first lateral opening facing a secondradial direction generally opposite the first radial direction; andsecond, third, and fourth branching stent-grafts, which are configuredassume radially-expanded states, wherein the first, the second, thethird, and the fourth stent-grafts are configured such that thebranching stent-grafts form respective blood-impervious seals with thefirst stent-graft around the distal inferior first lateral opening, thedistal superior first lateral opening, and the proximal superior firstlateral opening, respectively, when the branching stent-grafts aredisposed therethrough, respectively, and the first, the second, thethird, and the fourth stent-grafts are in their radially-expandedstates.
 27. The apparatus according to claim 26, wherein the firststent-graft comprises a first generally tubular support element and afirst covering element attached to the first support element so as to atleast partially cover the first support element, and the first coveringelement and the first support element are shaped so as to togetherdefine, when the first stent-graft is in its radially-expanded state,the proximal and the distal superior first lateral openings facing inthe first radial direction, and the distal inferior first lateralopening facing the second radial direction, and wherein the second, thethird, and the fourth branching stent-grafts comprise respectivegenerally tubular branching support elements and respective branchingcovering elements, attached to the branching support elements so as toat least partially cover the branching support elements, and the first,the second, the third, and the fourth stent-grafts are configured suchthat the branching covering elements form the respectiveblood-impervious seals with the first covering element around the distalinferior first lateral opening, the distal superior first lateralopening, and the proximal superior first lateral opening, respectively,when the branching stent-grafts are disposed therethrough, respectively,and the first, the second, the third, and the fourth stent-grafts are intheir radially-expanded states.
 28. The apparatus according to claim 26,wherein the distal inferior first lateral opening is not axially alignedwith either of the proximal or distal superior first lateral openings.29. The apparatus according to claim 28, wherein the distal inferiorfirst lateral opening does not axially overlap with either of theproximal or distal superior first lateral openings.
 30. Apparatuscomprising a multi-component stent-graft system, which comprises: afirst stent-graft, which is shaped so as to define, when in aradially-expanded state, a superior first lateral opening facing in afirst radial direction, and an inferior first lateral opening facing ina second radial direction generally opposite the first radial direction;a second stent-graft, which is configured to assume a radially-expandedstate, wherein the first and the second stent-grafts are configured suchthat the second stent-graft forms a blood-impervious seal with the firststent-graft around the superior first lateral opening when the secondstent-graft is disposed therethrough, and the first and the secondstent-grafts are in their radially-expanded states; a third stent-graft,which is shaped so as to define a third lateral opening through thethird stent-graft when the third stent-graft is in a radially-expandedstate; and a fourth stent-graft having first and second ends, whichstent-graft is configured to assume a radially-expanded state, whereinthe first, the third, and the fourth stent-grafts are configured suchthat, when the first, the third, and the fourth stent-grafts are intheir radially-expanded states, the fourth stent-graft formsblood-impervious seals with (a) the first stent-graft around theinferior first lateral opening when the first end of the fourthstent-graft is disposed therethrough, and (b) the third stent-graftaround the third lateral opening when the second end of the fourthstent-graft is disposed therethrough.
 31. The apparatus according toclaim 30, wherein the first stent-graft comprises a first generallytubular support element and a first covering element attached to thefirst support element so as to at least partially cover the firstsupport element, wherein the first covering element and the firstsupport element are shaped so as to together define, when the firststent-graft is in its radially-expanded state, the superior firstlateral opening facing in the first radial direction, and the inferiorfirst lateral opening facing in the second radial direction, wherein thesecond stent-graft comprises a second generally tubular support elementand a second covering element attached to the second support element soas to at least partially cover the second support element, wherein thefirst and the second stent-grafts are configured such that the secondcovering element forms the blood-impervious seal with the first coveringelement around the superior first lateral opening when the secondstent-graft is disposed therethrough, and the first and the secondstent-grafts are in their radially-expanded states, wherein the thirdstent-graft comprises a third generally tubular support element and athird covering element attached to the third support element so as to atleast partially cover the third support element, wherein the thirdcovering element and the third support element are shaped so as totogether define the third lateral opening through the third stent-graftwhen the third stent-graft is in its radially-expanded state, andwherein the fourth stent-graft comprises a fourth generally tubularsupport element and a fourth covering element attached to the fourthsupport element so as to at least partially cover the fourth supportelement, wherein the first, the third, and the fourth stent-grafts areconfigured such that, when the first, the third, and the fourthstent-grafts are in their radially-expanded states, the fourth coveringelement forms the blood-impervious seals with (a) the first coveringelement around the inferior first lateral opening when the first end ofthe fourth stent-graft is disposed therethrough, and (b) the thirdcovering element around the third lateral opening when the second end ofthe fourth stent-graft is disposed therethrough.
 32. The apparatusaccording to claim 30, wherein the inferior first lateral opening is notaxially aligned with the superior first lateral opening.
 33. Theapparatus according to claim 32, wherein the inferior first lateralopening does not axially overlap with the superior first lateralopening.
 34. Apparatus comprising a multi-component stent-graft system,which comprises: a first stent-graft, which is configured to assumeradially-expanded and radially-compressed states; a second stent-graft,which is configured to assume radially-expanded and radially-compressedstates; and a delivery tool, which comprises an outer tube, in which thefirst and the second stent-grafts are initially positioned at respectiveaxial sites within the outer tube, in their radially-compressed stateswithout being fixed to each other.
 35. The apparatus according to claim34, wherein the first and second stent-grafts are initially positionedin the outer tube such that at least one end of the first stent-graft iswithin a distance of a distal end of the outer tube, which distanceequals the sum of 2 cm and an axial length of the first stent-graft, andwherein the delivery tool is shaped so as to define first and secondstopper elements, which are configured and initially positioned toprevent movement of the first and the second stent-grafts, respectively,in a proximal direction away from the distal end of the outer tube. 36.The apparatus according to claim 35, wherein an inner surface of theouter tube is shaped so as to define the first and second stopperelements.
 37. The apparatus according to claim 35, wherein the deliverytool further comprises an inner longitudinal member, which is initiallypositioned such that first and second portions thereof are within thefirst and the second stent-grafts, respectively, and wherein the innerlongitudinal member is shaped so as to define the first and the secondstopper elements.
 38. The apparatus according to claim 37, wherein theinner longitudinal member is shaped so as to define a lumentherethrough.
 39. The apparatus according to claim 34, wherein the firstand the second stent-grafts are initially positioned in the outer tubesuch that at least one end of the first stent-graft is within a distanceof a distal end of the outer tube, which distance equals the sum of 2 cmand an axial length of the first stent-graft, wherein the delivery toolfurther comprises an inner longitudinal member, which is initiallypositioned such that first and second portions thereof are within thefirst and the second stent-grafts, respectively, and wherein the innerlongitudinal member is shaped so as to define a stopper element, whichis: configured and initially positioned to prevent movement of the firststent-graft in a proximal direction away from the distal end of theouter tube, and configured to be withdrawable in the proximal directionthrough the second stent-graft, and after being thus withdrawn, toprevent movement of the second stent-graft in the proximal direction.40. The apparatus according to claim 39, wherein an inner surface of theouter tube is shaped so as to define at least one pusher element, whichis configured to prevent movement of at least one of the first and thesecond stent-grafts in the proximal direction.
 41. The apparatusaccording to claim 39, wherein the delivery tool further comprises atleast one pusher element, which is configured to prevent movement of atleast one of the first and the second stent-grafts in the proximaldirection.
 42. The apparatus according to claim 39, wherein the innerlongitudinal member is shaped so as to define a lumen therethrough. 43.The apparatus according to claim 34, wherein the first stent-graft isinitially positioned in the outer tube such that at least one end of thefirst stent-graft is within a distance of a distal end of the outertube, which distance equals the sum of 2 cm and an axial length of thefirst stent-graft, and wherein the second stent-graft is initiallypositioned in the outer tube such that the first stent-graft islongitudinally between the distal end of the outer tube and the secondstent-graft.
 44. The apparatus according to claim 34, wherein the firststent-graft is shaped so as to define a first lateral opening.
 45. Theapparatus according to claim 44, wherein the first stent-graft comprisesa first generally tubular support element and a first covering element,which is attached to the first support element so as to at leastpartially cover the first support element, and the first coveringelement and the first support element are shaped so as to togetherdefine the first lateral opening, wherein the second stent-graftcomprises a second generally tubular support element and a secondcovering element, which is attached to the second support element so asto at least partially cover the second support element, and wherein thefirst and the second stent-grafts are configured such that the secondcovering element forms a blood-impervious seal with the first coveringelement around the first lateral opening when the second stent-graft isdisposed therethrough, and the first and the second stent-grafts are intheir radially-expanded states.
 46. The apparatus according to any oneof claims 1, 15, 26, 45, wherein a proximal end of the secondstent-graft is flared radially outward in a proximal direction, when thesecond stent-graft is in its radially-expanded state.
 47. The apparatusaccording to any one of claims 1, 15, 26, 30, and 34, wherein the secondstent-graft has a generally cylindrical shape when the secondstent-graft is unconstrained in its radially-expanded state.
 48. Theapparatus according to any one of claims 1, 15, 26, 30, and 34, whereinthe first and the second stent-grafts are configured for transluminaldelivery for transport to respective sites within a body lumen when intheir radially-compressed states.
 49. The apparatus according to claim9, wherein the second stent-graft is adapted for transluminal deliveryin its radially-compressed state through a portion of the firststent-graft and the first lateral opening, while the first stent-graftis in its radially-expanded state.
 50. The apparatus according to anyone of claims 1, 15, 26, 30, and 34, wherein the first stent-graftfurther comprises one or more radiopaque markers, located in a vicinityof the first lateral opening.
 51. The apparatus according to any one ofclaims 1, 15, 26, 30, and 34, wherein an axial length of the firststent-graft is between 5 and 30 cm, when the first stent-graft isunconstrained in its radially-expanded state.
 52. The apparatusaccording to any one of claims 1, 15, 26, 30, and 34, wherein an axiallength of the second stent-graft is between 5 and 20 cm, when the secondstent-graft is unconstrained in its radially-expanded state.
 53. Theapparatus according to any one of claims 1, 15, 26, 30, and 34, whereina greatest perimeter of the first stent-graft is between 4.5 and 19 cm,when the first stent-graft is unconstrained in its radially-expandedstate.
 54. The apparatus according to any one of claims 1, 15, 26, 30,and 34, wherein a greatest perimeter of the second stent-graft isbetween 9 and 22 cm, when the second stent-graft is unconstrained in itsradially-expanded state.
 55. The apparatus according to any one ofclaims 1, 15, 26, 30, and 34, wherein a perimeter of one end of thefirst stent-graft is between 7.5 and 15 cm, when the first stent-graftis unconstrained in its radially-expanded state.
 56. The apparatusaccording to any one of claims 1, 15, 26, 30, and 34, wherein aperimeter of one end of the second stent-graft is between 5 and 15.4 cm,when the second stent-graft is unconstrained in its radially-expandedstate.
 57. The apparatus according to any one of claims 2, 16, 27, 31,and 45, wherein, when the second stent-graft is disposed through thefirst lateral opening and the first and the second stent-grafts are intheir radially-expanded states: a proximal portion of the second supportelement is disposed within the first stent-graft, and the secondcovering element does not fully cover the proximal portion of the secondsupport element, thereby allowing blood flow through the firststent-graft.
 58. The apparatus according to claim 57, wherein an axialportion of the proximal portion of the second support element having alength of at least 1 cm has a perimeter that is at least 10% greaterthan a perimeter of a portion of the first stent-graft in which theproximal portion of the second support element is disposed, when thefirst and second stent-grafts are in their radially-expanded states. 59.The apparatus according to claim 57, wherein the second covering elementis configured to cover a distal sub-portion, and not a proximalsub-portion, of the proximal portion of the second support element. 60.The apparatus according to any one of claims 2, 16, 27, 31, and 45,wherein a section of the second covering element extends through thefirst lateral opening and into a portion of the first stent-graft whenthe second stent-graft is disposed through the first lateral opening.61. The apparatus according to any one of claims 2, 16, 27, 31, and 45,wherein the first covering element only partially covers the firstsupport element.
 62. The apparatus according to any one of claims 2, 16,27, 31, 45, wherein at least one of the first and the second supportelements is shaped so as to define one or morecircumferentially-disposed, radially-protruding barbs, when the at leastone of the first and second support elements is in its radially-expandedstate.
 63. A method for treating a patient, comprising: transvascularlyintroducing and positioning a first stent-graft, which is shaped so asto define one or more first lateral openings, such that (a) a proximalportion of the first stent-graft, including a proximal end of thefirst-stent-graft, is in an upper part of a descending aorta, (b) adistal portion of the first stent-graft, including a distal end of thefirst stent-graft, is in a branch of an aortic arch, and (c) one of theone or more first lateral openings is disposed within the aortic archfacing upstream, generally toward an ascending aorta; andtransvascularly introducing and passing a second stent-graft through theproximal portion of the first stent-graft such that the secondstent-graft is disposed through the one of the one or more first lateralopenings and is disposed partially in the aortic arch, and forms ablood-impervious seal with the first stent-graft around the one of theone or more first lateral openings.
 64. The method according to claim63, wherein the branch is a left subclavian artery, and whereinpositioning the first stent-graft comprises positioning the firststent-graft such that the distal portion of the first stent-graft,including the distal end of the first stent-graft, is in the leftsubclavian artery.
 65. The method according to claim 64, wherein passingcomprises passing the second stent-graft through the proximal portion ofthe first stent-graft such that the second stent-graft is disposedthrough the one of the one or more first lateral openings and isdisposed partially in the aortic arch, and a distal portion of thesecond stent-graft, including a distal end of the second stent-graft, isin a left common carotid artery.
 66. The method according to claim 63,wherein the branch is a brachiocephalic artery, wherein the firstlateral openings include proximal and distal superior first lateralopenings, and a distal inferior first lateral opening, whereinpositioning the first stent-graft comprises positioning the firststent-graft such that (a) the distal portion of the first stent-graft,including the distal end of the first stent-graft, is in thebrachiocephalic artery, (b) the distal inferior first lateral openingfaces upstream, generally toward the ascending aorta, and (c) theproximal and the distal superior first lateral openings face and arealigned with a left subclavian artery and a left common carotid artery,respectively, and wherein passing the second stent-graft comprisespassing the second stent-graft through the proximal portion of the firststent-graft such that the second stent-graft is disposed through thedistal inferior first lateral opening and is disposed partially in thedistal portion of the main blood vessel.
 67. The method according toclaim 66, further comprising transvascularly introducing and positioningthird and fourth stent-grafts through the proximal portion of the firststent-graft such the third and fourth stent-grafts are disposed throughthe proximal and the distal superior first lateral openings,respectively, and are disposed partially in the left subclavian arteryand the left common carotid artery, respectively, and formblood-impervious seals with the first stent-graft around the proximaland the distal superior first lateral openings, respectively.
 68. Themethod according to claim 63, wherein the branch is a left commoncarotid artery, wherein the first lateral openings include a superiorfirst lateral opening and an inferior first lateral opening, whereinpositioning the first stent-graft comprises positioning the firststent-graft such that (a) the distal portion of the first stent-graft,including the distal end of the first stent-graft, is in the left commoncarotid artery, (b) the inferior first lateral opening faces upstream,generally toward the ascending aorta, and (c) the superior first lateralopening faces and is aligned with a left subclavian artery, and furthercomprising transvascularly introducing a third stent-graft via a rightsubclavian artery, and positioning the third stent-graft such that aproximal portion of the third stent-graft, including a proximal end ofthe third stent-graft is disposed in a brachiocephalic artery, and adistal portion of the third stent-graft, including a proximal end of thethird-stent graft, is disposed in a portion of at least one blood vesselselected from the group consisting of: the aortic arch, and an upperpart of an ascending aorta, and a third lateral opening defined by thethird stent-graft faces upstream, generally toward the descending aorta,wherein passing the second stent-graft comprises passing the secondstent-graft through the proximal portion of the first stent-graft suchthat the second stent-graft is disposed through the inferior firstlateral opening and the third lateral opening, and is disposed partiallyin the aortic arch.
 69. The method according to claim 68, furthercomprising transvascularly introducing and positioning a fourthstent-graft through the proximal portion of the first stent-graft suchthe fourth stent-graft is disposed through the superior first lateralopening, and is disposed partially in the left subclavian artery, andforms a blood-impervious seal with the first stent-graft around thesuperior first lateral opening.
 70. The method according to claim 63,wherein transvascularly introducing the first and the secondstent-grafts comprises separately transvascularly introducing the firstand the second stent-grafts while they are not fixed to one another. 71.The method according to claim 63, wherein transvascularly introducingthe first stent-graft comprises transvascularly introducing the firststent-graft while in a radially-compressed state, and transitioning thefirst stent-graft to a radially-expanded state after positioning thefirst stent-graft, wherein transvascularly introducing the secondstent-graft comprises transvascularly introducing the second stent-graftwhile in a radially-compressed state, wherein passing the secondstent-graft comprising passing the second stent-graft, while in itsradially-compressed state, through the proximal portion after the firststent-graft has been transitioned to its radially-expanded state, andwherein the method further comprises, after passing the secondstent-graft, transitioning, without inverting, the second stent-graftfrom a radially-compressed state to a radially-expanded state.
 72. Themethod according to claim 71, wherein transitioning the firststent-graft comprises transitioning the first stent-graft to itsradially-expanded state in which a first perimeter of a first end of thefirst stent-graft equals at least 200% of a second perimeter of a secondend of the first stent-graft.
 73. The method according to claim 72,wherein the first perimeter equals at least 250% of the secondperimeter.
 74. The method according to claim 73, wherein the firstperimeter equals at least 400% of the second perimeter.
 75. The methodaccording to claim 72, wherein the first perimeter is between 7.5 and 15cm, and the second perimeter is between 2.5 and 5.7 cm.
 76. The methodaccording to claim 63, further comprising identifying that the patientsuffers from a thoracic aortic aneurysm of an aortic arch, and whereintransvascularly introducing the first stent-graft comprisestransvascularly introducing the first stent-graft responsively to theidentifying.
 77. A method for treating a patient, comprising:transvascularly introducing and positioning a first stent intovasculature of the patient; transvascularly introducing and passing asecond stent through a portion of the first stent such that the secondstent is disposed through a first lateral opening defined by the firststent; and transvascularly introducing and passing a third stentsequentially through (a) the portion of the first stent, (b) the firstlateral opening, and (c) a portion of the second stent, such that thethird stent is disposed through a second lateral opening defined by thesecond stent.
 78. The method according to claim 77, wherein the firstand second stents include respective first and second support elementsand respective first and second covering elements attached to the firstand second support elements, respectively, and wherein passing thesecond stent comprises disposing the second stent through the firstlateral opening such that the second covering element forms ablood-impervious seal with the first covering element around the firstlateral opening.
 79. The method according to claim 77, wherein thesecond and third stents include respective second and third supportelements and respective second and third covering elements attached tothe second and third support elements, respectively, and wherein passingthe third stent comprises disposing the third stent through the secondlateral opening such that the third covering element forms ablood-impervious seal with the second covering element around the secondlateral opening.
 80. The method according to claim 77, whereintransvascularly introducing the first, the second, and the third stentcomprises separately transvascularly introducing the first, the second,and the third stent while they are not fixed to one another.
 81. Themethod according to claim 77, wherein passing the third stent comprisespassing the third stent while the first and the second stent are inradially-expanded states, and the third stent is in aradially-compressed state.
 82. The method according to claim 77, furthercomprising transvascularly introducing and passing a fourth stentsequentially through (a) the portion of the first stent, (b) the firstlateral opening, (c) the portion of the second stent, (d) the secondlateral opening, and (e) a portion of the third stent, such that thefourth stent is disposed through a third lateral opening defined by thethird stent.
 83. The method according to claim 82, wherein passing thefourth stent comprises passing the fourth stent while the first, thesecond, and the third stent are in radially-expanded states, and thefourth stent is in a radially-compressed state.
 84. The method accordingto claim 77, wherein positioning the first stent comprises positioningthe first stent such that (a) a proximal portion of the first stent,including a proximal end of the first-stent, is in a proximal portion ofa main blood vessel, (b) a distal portion of the first stent, includinga distal end of the first stent, is in a branching blood vessel thatbranches from the main blood vessel at a bifurcation, and (c) the firstlateral opening is disposed within the main blood vessel facing toward adistal portion of the main blood vessel, which distal portion is distalto the bifurcation, and wherein passing the second stent comprisespassing the second stent through the portion of the first stent suchthat the second stent is disposed through the first lateral opening andis disposed partially in the distal portion of the main blood vessel.85. The method according to claim 84, wherein the main blood vessel isan aorta, the branching blood vessel is a branch of an aortic arch, andthe distal portion of the main body lumen is a portion of the aorticarch, wherein positioning the first stent comprises positioning thefirst stent such that the proximal portion of the first stent, includingthe proximal end of the first-stent, is in an upper part of a descendingaorta, the distal portion of the first stent, including the distal endof the first stent, is in the branch of the aortic arch, and the firstlateral opening faces upstream, generally toward an ascending aorta, andwherein passing comprises passing the second stent through the proximalportion of the first stent such that the second stent is disposedthrough the first lateral opening and is disposed partially in theaortic arch.
 86. The method according to claim 85, wherein the branch isa left subclavian artery, and wherein positioning the first stentcomprises positioning the first stent such that the distal portion ofthe first stent, including the distal end of the first stent, is in theleft subclavian artery.
 87. The method according to claim 86, whereinpassing comprises passing the second stent through the proximal portionof the first stent such that the second stent is disposed through thefirst lateral opening and is disposed partially in the aortic arch, anda distal portion of the second stent, including a distal end of thesecond stent, is in a left common carotid artery.
 88. The methodaccording to claim 77, wherein transvascularly introducing the firststent comprises transvascularly introducing the first stent while in aradially-compressed state, and transitioning the first stent to aradially-expanded state after positioning the first stent, whereintransvascularly introducing the second stent comprises transvascularlyintroducing the second stent while in a radially-compressed state,wherein passing the second stent comprising passing the second stent,while in its radially-compressed state, through the proximal portionafter the first stent has been transitioned to its radially-expandedstate, and wherein the method further comprises, after passing thesecond stent, transitioning, without inverting, the second stent from aradially-compressed state to a radially-expanded state.
 89. The methodaccording to claim 88, wherein transitioning the first stent comprisestransitioning the first stent to its radially-expanded state in which afirst perimeter of a first end of the first stent equals at least 200%of a second perimeter of a second end of the first stent.
 90. The methodaccording to claim 89, wherein the first perimeter equals at least 250%of the second perimeter.
 91. The method according to claim 90, whereinthe first perimeter equals at least 400% of the second perimeter. 92.The method according to claim 89, wherein the first perimeter is between7.5 and 15 cm, and the second perimeter is between 2.5 and 5.7 cm. 93.The method according to claim 77, further comprising identifying thatthe patient suffers from a thoracic aortic aneurysm of an aortic arch,and wherein transvascularly introducing the first stent comprisestransvascularly introducing the first stent responsively to theidentifying.
 94. A method comprising: transvascularly introducing, intovasculature of a patient, a delivery tool, which includes an outer tube,in which first and second stents are initially positioned at respectiveaxial sites within the outer tube, in radially-compressed states withoutbeing fixed to each other; deploying the first stent from a distal endof the outer tube, such that the first stent transitions to aradially-expanded state; and after the first stent transitions to theradially-expanded state, deploying the second stent from the distal endof the outer tube, such that the second stent transitions to aradially-expanded state.
 95. The method according to claim 94, whereinthe delivery tool is shaped so as to define first and second stopperelements, which are configured and initially positioned to preventmovement of the first and second stents, respectively, in a proximaldirection away from the distal end of the outer tube, wherein deployingthe first stent comprises withdrawing, in the proximal direction, theouter tube, such that the first stopper element prevents the movement ofthe first stent in the proximal direction, and wherein deploying thesecond stent comprises withdrawing the outer tube in the proximaldirection, such that the second stopper element prevents the movement ofthe second stent in the proximal direction.
 96. The method according toclaim 95, wherein an inner surface of the outer tube is shaped so as todefine the first and second stopper elements.
 97. The method accordingto claim 95, wherein the delivery tool further includes an innerlongitudinal member, which is initially positioned such that first andsecond portions thereof are within the first and second stents,respectively, and wherein the inner longitudinal member is shaped so asto define the first and second stopper elements.
 98. The methodaccording to claim 94, wherein the delivery tool further includes aninner longitudinal member, which is initially positioned such that firstand second portions thereof are within the first and second stents,respectively, wherein the inner longitudinal member is shaped so as todefine a stopper element, which is (a) configured and initiallypositioned to prevent movement of the first stent in a proximaldirection away from the distal end of the outer tube, and (b) configuredto be withdrawable in the proximal direction through the second stent,and after being thus withdrawn, to prevent movement of the second stentin the proximal direction, wherein deploying the first stent compriseswithdrawing the outer tube in the proximal direction, such that thestopper element prevents the movement of the first stent in the proximaldirection, and wherein deploying the second stent comprises: withdrawingthe inner longitudinal member in the proximal direction, such that thestopper element passes through the second stent; and withdrawing theouter tube in the proximal direction, such that the stopper elementprevents the movement of the second stent in the proximal direction. 99.A method for treating a patient, comprising: transvascularly introducinga stent-graft into vasculature of the patient; and positioning thestent-graft such that (a) a proximal portion of the stent-graft,including a proximal end of the first-stent-graft, is in abrachiocephalic artery, (b) a distal portion of the stent-graft,including a distal end of the stent-graft, is disposed in a portion ofat least one blood vessel selected from the group consisting of: anaortic arch, and an upper part of an ascending aorta, and (c) a lateralopening defined by the stent-graft is disposed in the aortic arch facinggenerally toward a descending aorta.
 100. The method according to claim99, wherein the stent-graft is a first stent-graft, and furthercomprising transvascularly introducing and positioning a secondstent-graft through the lateral opening, such that the secondstent-graft forms a blood-impervious seal with the first stent-graftaround the lateral opening.
 101. A method for assembling amulti-component stent-graft system, the method comprising: providing (a)a first generally tubular stent-graft, which is shaped so as to define afirst lateral opening when the first stent-graft is in aradially-expanded state, (b) a second generally tubular stent-graft,which is shaped so as to define a second lateral opening when the secondstent-graft is in a radially-expanded state, and (c) a third generallytubular stent-graft; while the first stent-graft is in itsradially-expanded state and the second stent-graft is in aradially-compressed state, disposing the second stent-graft through thefirst lateral opening, and causing the second stent-graft to transitionto its radially-expanded state, such that the second stent-graft forms ablood-impervious seal with the first stent-graft around the firstlateral opening; and while the second stent-graft is in itsradially-expanded state and the third stent-graft is in aradially-compressed state, disposing the third stent-graft through thesecond lateral opening, and causing the third stent-graft to transitionto a radially-expanded state, such that the third stent-graft forms ablood-impervious seal with the second stent-graft around the secondlateral opening.
 102. The method according to claim 101, wherein thethird stent-graft is shaped so as to define a third lateral opening whenin its radially-expanded state, and wherein the method furthercomprises: providing a fourth generally tubular stent-graft; and whilethe third stent-graft is in its radially-expanded state and the fourthstent-graft is in a radially-compressed state, disposing the fourthstent-graft through the third lateral opening, and causing the fourthstent-graft to transition to a radially-expanded state, such that thefourth stent-graft forms a blood-impervious seal with the thirdstent-graft around the third lateral opening.
 103. A method forassembling a multi-component stent-graft system, the method comprising:providing (a) a first generally tubular stent-graft, which, whenunconstrained in a radially-expanded state: (i) defines a first lateralopening, and (ii) has a first perimeter of a first end thereof thatequals at least 200% of a second perimeter of a second end thereof, and(b) a second generally tubular stent-graft; and while the firststent-graft is in its radially-expanded state and the second stent-graftis in a radially-compressed state, disposing the second stent-graftthrough the first lateral opening, and causing the second stent-graft totransition to a radially-expanded state, such that the secondstent-graft forms a blood-impervious seal with the first stent-graftaround the first lateral opening.
 104. A method for assembling amulti-component stent-graft system, the method comprising: providing (a)a first stent-graft, which is shaped so as to define, when in aradially-expanded state, proximal and distal superior first lateralopenings facing in a first radial direction, and a distal inferior firstlateral opening facing a second radial direction generally opposite thefirst radial direction, and (b) second, third, and fourth branchingstent-grafts; and while the first stent-graft is in itsradially-expanded state and the second stent-graft is in aradially-compressed state, disposing the second stent-graft through thedistal inferior first lateral opening, and causing the secondstent-graft to transition to a radially-expanded state, such that thesecond stent-graft forms a blood-impervious seal with the firststent-graft around the distal inferior first lateral opening; while thefirst stent-graft is in its radially-expanded state and the thirdstent-graft is in a radially-compressed state, disposing the thirdstent-graft through the distal superior first lateral opening, andcausing the third stent-graft to transition to a radially-expandedstate, such that the third stent-graft forms a blood-impervious sealwith the first stent-graft around the distal superior first lateralopening; and while the first stent-graft is in its radially-expandedstate and the fourth stent-graft is in a radially-compressed state,disposing the fourth stent-graft through the proximal superior firstlateral opening, and causing the fourth stent-graft to transition to aradially-expanded state, such that the fourth stent-graft forms ablood-impervious seal with the first stent-graft around the proximalsuperior first lateral opening.
 105. A method for assembling amulti-component stent-graft system, the method comprising: providing (a)a first stent-graft, which is shaped so as to define, when in aradially-expanded state, a superior first lateral opening facing in afirst radial direction, and an inferior first lateral opening facing ina second radial direction generally opposite the first radial direction,(b) a second stent-graft, (c) a third stent-graft, which is shaped so asto define a third lateral opening through the third stent-graft when thethird stent-graft is in a radially-expanded state, and (d) a fourthstent-graft; while the first stent-graft is in its radially-expandedstate and the second stent-graft is in a radially-compressed state,disposing the second stent-graft through the superior first lateralopening, and causing the second stent-graft to transition to aradially-expanded state, such that the second stent-graft forms ablood-impervious seal with the first stent-graft around the superiorfirst lateral opening; and while the first and the third stent-graftsare in their radially-expanded states and the fourth stent-graft is in aradially-compressed state, disposing first and second ends of the fourthstent-graft through the inferior first lateral opening and the thirdlateral opening, respectively, and causing the fourth stent-graft totransition to a radially-expanded state, such that the fourthstent-graft forms blood-impervious seals with the first stent-graftaround the inferior first lateral opening and the third stent-graftaround the third lateral opening.